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authorIngo Molnar2009-06-11 17:55:42 +0200
committerIngo Molnar2009-06-11 17:55:42 +0200
commit940010c5a314a7bd9b498593bc6ba1718ac5aec5 (patch)
treed141e08ced08c40c6a8e3ab2cdecde5ff14e560f /Documentation
parent8dc8e5e8bc0ce00b0f656bf972f67cd8a72759e5 (diff)
parent991ec02cdca33b03a132a0cacfe6f0aa0be9aa8d (diff)
Merge branch 'linus' into perfcounters/core
Conflicts: arch/x86/kernel/irqinit.c arch/x86/kernel/irqinit_64.c arch/x86/kernel/traps.c arch/x86/mm/fault.c include/linux/sched.h kernel/exit.c
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-devices-cache_disable18
-rw-r--r--Documentation/DMA-API.txt12
-rw-r--r--Documentation/DocBook/Makefile3
-rw-r--r--Documentation/DocBook/tracepoint.tmpl89
-rw-r--r--Documentation/RCU/trace.txt102
-rw-r--r--Documentation/futex-requeue-pi.txt131
-rw-r--r--Documentation/kernel-parameters.txt50
-rw-r--r--Documentation/memory-barriers.txt129
-rw-r--r--Documentation/scheduler/sched-rt-group.txt20
-rw-r--r--Documentation/trace/events.txt90
-rw-r--r--Documentation/trace/ftrace.txt17
-rw-r--r--Documentation/trace/power.txt17
-rw-r--r--Documentation/x86/boot.txt122
-rw-r--r--Documentation/x86/x86_64/boot-options.txt5
-rw-r--r--Documentation/x86/x86_64/mm.txt9
15 files changed, 751 insertions, 63 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-cache_disable b/Documentation/ABI/testing/sysfs-devices-cache_disable
new file mode 100644
index 000000000000..175bb4f70512
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-cache_disable
@@ -0,0 +1,18 @@
+What: /sys/devices/system/cpu/cpu*/cache/index*/cache_disable_X
+Date: August 2008
+KernelVersion: 2.6.27
+Contact: mark.langsdorf@amd.com
+Description: These files exist in every cpu's cache index directories.
+ There are currently 2 cache_disable_# files in each
+ directory. Reading from these files on a supported
+ processor will return that cache disable index value
+ for that processor and node. Writing to one of these
+ files will cause the specificed cache index to be disabled.
+
+ Currently, only AMD Family 10h Processors support cache index
+ disable, and only for their L3 caches. See the BIOS and
+ Kernel Developer's Guide at
+ http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31116-Public-GH-BKDG_3.20_2-4-09.pdf
+ for formatting information and other details on the
+ cache index disable.
+Users: joachim.deguara@amd.com
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index d9aa43d78bcc..25fb8bcf32a2 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -704,12 +704,24 @@ this directory the following files can currently be found:
The current number of free dma_debug_entries
in the allocator.
+ dma-api/driver-filter
+ You can write a name of a driver into this file
+ to limit the debug output to requests from that
+ particular driver. Write an empty string to
+ that file to disable the filter and see
+ all errors again.
+
If you have this code compiled into your kernel it will be enabled by default.
If you want to boot without the bookkeeping anyway you can provide
'dma_debug=off' as a boot parameter. This will disable DMA-API debugging.
Notice that you can not enable it again at runtime. You have to reboot to do
so.
+If you want to see debug messages only for a special device driver you can
+specify the dma_debug_driver=<drivername> parameter. This will enable the
+driver filter at boot time. The debug code will only print errors for that
+driver afterwards. This filter can be disabled or changed later using debugfs.
+
When the code disables itself at runtime this is most likely because it ran
out of dma_debug_entries. These entries are preallocated at boot. The number
of preallocated entries is defined per architecture. If it is too low for you
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index b1eb661e6302..9632444f6c62 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -13,7 +13,8 @@ DOCBOOKS := z8530book.xml mcabook.xml device-drivers.xml \
gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
mac80211.xml debugobjects.xml sh.xml regulator.xml \
- alsa-driver-api.xml writing-an-alsa-driver.xml
+ alsa-driver-api.xml writing-an-alsa-driver.xml \
+ tracepoint.xml
###
# The build process is as follows (targets):
diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
new file mode 100644
index 000000000000..b0756d0fd579
--- /dev/null
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -0,0 +1,89 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+
+<book id="Tracepoints">
+ <bookinfo>
+ <title>The Linux Kernel Tracepoint API</title>
+
+ <authorgroup>
+ <author>
+ <firstname>Jason</firstname>
+ <surname>Baron</surname>
+ <affiliation>
+ <address>
+ <email>jbaron@redhat.com</email>
+ </address>
+ </affiliation>
+ </author>
+ </authorgroup>
+
+ <legalnotice>
+ <para>
+ This documentation is free software; you can redistribute
+ it and/or modify it under the terms of the GNU General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later
+ version.
+ </para>
+
+ <para>
+ This program is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ See the GNU General Public License for more details.
+ </para>
+
+ <para>
+ You should have received a copy of the GNU General Public
+ License along with this program; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ MA 02111-1307 USA
+ </para>
+
+ <para>
+ For more details see the file COPYING in the source
+ distribution of Linux.
+ </para>
+ </legalnotice>
+ </bookinfo>
+
+ <toc></toc>
+ <chapter id="intro">
+ <title>Introduction</title>
+ <para>
+ Tracepoints are static probe points that are located in strategic points
+ throughout the kernel. 'Probes' register/unregister with tracepoints
+ via a callback mechanism. The 'probes' are strictly typed functions that
+ are passed a unique set of parameters defined by each tracepoint.
+ </para>
+
+ <para>
+ From this simple callback mechanism, 'probes' can be used to profile, debug,
+ and understand kernel behavior. There are a number of tools that provide a
+ framework for using 'probes'. These tools include Systemtap, ftrace, and
+ LTTng.
+ </para>
+
+ <para>
+ Tracepoints are defined in a number of header files via various macros. Thus,
+ the purpose of this document is to provide a clear accounting of the available
+ tracepoints. The intention is to understand not only what tracepoints are
+ available but also to understand where future tracepoints might be added.
+ </para>
+
+ <para>
+ The API presented has functions of the form:
+ <function>trace_tracepointname(function parameters)</function>. These are the
+ tracepoints callbacks that are found throughout the code. Registering and
+ unregistering probes with these callback sites is covered in the
+ <filename>Documentation/trace/*</filename> directory.
+ </para>
+ </chapter>
+
+ <chapter id="irq">
+ <title>IRQ</title>
+!Iinclude/trace/events/irq.h
+ </chapter>
+
+</book>
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index 068848240a8b..02cced183b2d 100644
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -192,23 +192,24 @@ rcu/rcuhier (which displays the struct rcu_node hierarchy).
The output of "cat rcu/rcudata" looks as follows:
rcu:
- 0 c=4011 g=4012 pq=1 pqc=4011 qp=0 rpfq=1 rp=3c2a dt=23301/73 dn=2 df=1882 of=0 ri=2126 ql=2 b=10
- 1 c=4011 g=4012 pq=1 pqc=4011 qp=0 rpfq=3 rp=39a6 dt=78073/1 dn=2 df=1402 of=0 ri=1875 ql=46 b=10
- 2 c=4010 g=4010 pq=1 pqc=4010 qp=0 rpfq=-5 rp=1d12 dt=16646/0 dn=2 df=3140 of=0 ri=2080 ql=0 b=10
- 3 c=4012 g=4013 pq=1 pqc=4012 qp=1 rpfq=3 rp=2b50 dt=21159/1 dn=2 df=2230 of=0 ri=1923 ql=72 b=10
- 4 c=4012 g=4013 pq=1 pqc=4012 qp=1 rpfq=3 rp=1644 dt=5783/1 dn=2 df=3348 of=0 ri=2805 ql=7 b=10
- 5 c=4012 g=4013 pq=0 pqc=4011 qp=1 rpfq=3 rp=1aac dt=5879/1 dn=2 df=3140 of=0 ri=2066 ql=10 b=10
- 6 c=4012 g=4013 pq=1 pqc=4012 qp=1 rpfq=3 rp=ed8 dt=5847/1 dn=2 df=3797 of=0 ri=1266 ql=10 b=10
- 7 c=4012 g=4013 pq=1 pqc=4012 qp=1 rpfq=3 rp=1fa2 dt=6199/1 dn=2 df=2795 of=0 ri=2162 ql=28 b=10
+rcu:
+ 0 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=10951/1 dn=0 df=1101 of=0 ri=36 ql=0 b=10
+ 1 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=16117/1 dn=0 df=1015 of=0 ri=0 ql=0 b=10
+ 2 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1445/1 dn=0 df=1839 of=0 ri=0 ql=0 b=10
+ 3 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=6681/1 dn=0 df=1545 of=0 ri=0 ql=0 b=10
+ 4 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=1003/1 dn=0 df=1992 of=0 ri=0 ql=0 b=10
+ 5 c=17829 g=17830 pq=1 pqc=17829 qp=1 dt=3887/1 dn=0 df=3331 of=0 ri=4 ql=2 b=10
+ 6 c=17829 g=17829 pq=1 pqc=17829 qp=0 dt=859/1 dn=0 df=3224 of=0 ri=0 ql=0 b=10
+ 7 c=17829 g=17830 pq=0 pqc=17829 qp=1 dt=3761/1 dn=0 df=1818 of=0 ri=0 ql=2 b=10
rcu_bh:
- 0 c=-268 g=-268 pq=1 pqc=-268 qp=0 rpfq=-145 rp=21d6 dt=23301/73 dn=2 df=0 of=0 ri=0 ql=0 b=10
- 1 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-170 rp=20ce dt=78073/1 dn=2 df=26 of=0 ri=5 ql=0 b=10
- 2 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-83 rp=fbd dt=16646/0 dn=2 df=28 of=0 ri=4 ql=0 b=10
- 3 c=-268 g=-268 pq=1 pqc=-268 qp=0 rpfq=-105 rp=178c dt=21159/1 dn=2 df=28 of=0 ri=2 ql=0 b=10
- 4 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-30 rp=b54 dt=5783/1 dn=2 df=32 of=0 ri=0 ql=0 b=10
- 5 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-29 rp=df5 dt=5879/1 dn=2 df=30 of=0 ri=3 ql=0 b=10
- 6 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-28 rp=788 dt=5847/1 dn=2 df=32 of=0 ri=0 ql=0 b=10
- 7 c=-268 g=-268 pq=1 pqc=-268 qp=1 rpfq=-53 rp=1098 dt=6199/1 dn=2 df=30 of=0 ri=3 ql=0 b=10
+ 0 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=10951/1 dn=0 df=0 of=0 ri=0 ql=0 b=10
+ 1 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=16117/1 dn=0 df=13 of=0 ri=0 ql=0 b=10
+ 2 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1445/1 dn=0 df=15 of=0 ri=0 ql=0 b=10
+ 3 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=6681/1 dn=0 df=9 of=0 ri=0 ql=0 b=10
+ 4 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=1003/1 dn=0 df=15 of=0 ri=0 ql=0 b=10
+ 5 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3887/1 dn=0 df=15 of=0 ri=0 ql=0 b=10
+ 6 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=859/1 dn=0 df=15 of=0 ri=0 ql=0 b=10
+ 7 c=-275 g=-275 pq=1 pqc=-275 qp=0 dt=3761/1 dn=0 df=15 of=0 ri=0 ql=0 b=10
The first section lists the rcu_data structures for rcu, the second for
rcu_bh. Each section has one line per CPU, or eight for this 8-CPU system.
@@ -253,12 +254,6 @@ o "pqc" indicates which grace period the last-observed quiescent
o "qp" indicates that RCU still expects a quiescent state from
this CPU.
-o "rpfq" is the number of rcu_pending() calls on this CPU required
- to induce this CPU to invoke force_quiescent_state().
-
-o "rp" is low-order four hex digits of the count of how many times
- rcu_pending() has been invoked on this CPU.
-
o "dt" is the current value of the dyntick counter that is incremented
when entering or leaving dynticks idle state, either by the
scheduler or by irq. The number after the "/" is the interrupt
@@ -305,6 +300,9 @@ o "b" is the batch limit for this CPU. If more than this number
of RCU callbacks is ready to invoke, then the remainder will
be deferred.
+There is also an rcu/rcudata.csv file with the same information in
+comma-separated-variable spreadsheet format.
+
The output of "cat rcu/rcugp" looks as follows:
@@ -411,3 +409,63 @@ o Each element of the form "1/1 0:127 ^0" represents one struct
For example, the first entry at the lowest level shows
"^0", indicating that it corresponds to bit zero in
the first entry at the middle level.
+
+
+The output of "cat rcu/rcu_pending" looks as follows:
+
+rcu:
+ 0 np=255892 qsp=53936 cbr=0 cng=14417 gpc=10033 gps=24320 nf=6445 nn=146741
+ 1 np=261224 qsp=54638 cbr=0 cng=25723 gpc=16310 gps=2849 nf=5912 nn=155792
+ 2 np=237496 qsp=49664 cbr=0 cng=2762 gpc=45478 gps=1762 nf=1201 nn=136629
+ 3 np=236249 qsp=48766 cbr=0 cng=286 gpc=48049 gps=1218 nf=207 nn=137723
+ 4 np=221310 qsp=46850 cbr=0 cng=26 gpc=43161 gps=4634 nf=3529 nn=123110
+ 5 np=237332 qsp=48449 cbr=0 cng=54 gpc=47920 gps=3252 nf=201 nn=137456
+ 6 np=219995 qsp=46718 cbr=0 cng=50 gpc=42098 gps=6093 nf=4202 nn=120834
+ 7 np=249893 qsp=49390 cbr=0 cng=72 gpc=38400 gps=17102 nf=41 nn=144888
+rcu_bh:
+ 0 np=146741 qsp=1419 cbr=0 cng=6 gpc=0 gps=0 nf=2 nn=145314
+ 1 np=155792 qsp=12597 cbr=0 cng=0 gpc=4 gps=8 nf=3 nn=143180
+ 2 np=136629 qsp=18680 cbr=0 cng=0 gpc=7 gps=6 nf=0 nn=117936
+ 3 np=137723 qsp=2843 cbr=0 cng=0 gpc=10 gps=7 nf=0 nn=134863
+ 4 np=123110 qsp=12433 cbr=0 cng=0 gpc=4 gps=2 nf=0 nn=110671
+ 5 np=137456 qsp=4210 cbr=0 cng=0 gpc=6 gps=5 nf=0 nn=133235
+ 6 np=120834 qsp=9902 cbr=0 cng=0 gpc=6 gps=3 nf=2 nn=110921
+ 7 np=144888 qsp=26336 cbr=0 cng=0 gpc=8 gps=2 nf=0 nn=118542
+
+As always, this is once again split into "rcu" and "rcu_bh" portions.
+The fields are as follows:
+
+o "np" is the number of times that __rcu_pending() has been invoked
+ for the corresponding flavor of RCU.
+
+o "qsp" is the number of times that the RCU was waiting for a
+ quiescent state from this CPU.
+
+o "cbr" is the number of times that this CPU had RCU callbacks
+ that had passed through a grace period, and were thus ready
+ to be invoked.
+
+o "cng" is the number of times that this CPU needed another
+ grace period while RCU was idle.
+
+o "gpc" is the number of times that an old grace period had
+ completed, but this CPU was not yet aware of it.
+
+o "gps" is the number of times that a new grace period had started,
+ but this CPU was not yet aware of it.
+
+o "nf" is the number of times that this CPU suspected that the
+ current grace period had run for too long, and thus needed to
+ be forced.
+
+ Please note that "forcing" consists of sending resched IPIs
+ to holdout CPUs. If that CPU really still is in an old RCU
+ read-side critical section, then we really do have to wait for it.
+ The assumption behing "forcing" is that the CPU is not still in
+ an old RCU read-side critical section, but has not yet responded
+ for some other reason.
+
+o "nn" is the number of times that this CPU needed nothing. Alert
+ readers will note that the rcu "nn" number for a given CPU very
+ closely matches the rcu_bh "np" number for that same CPU. This
+ is due to short-circuit evaluation in rcu_pending().
diff --git a/Documentation/futex-requeue-pi.txt b/Documentation/futex-requeue-pi.txt
new file mode 100644
index 000000000000..9dc1ff4fd536
--- /dev/null
+++ b/Documentation/futex-requeue-pi.txt
@@ -0,0 +1,131 @@
+Futex Requeue PI
+----------------
+
+Requeueing of tasks from a non-PI futex to a PI futex requires
+special handling in order to ensure the underlying rt_mutex is never
+left without an owner if it has waiters; doing so would break the PI
+boosting logic [see rt-mutex-desgin.txt] For the purposes of
+brevity, this action will be referred to as "requeue_pi" throughout
+this document. Priority inheritance is abbreviated throughout as
+"PI".
+
+Motivation
+----------
+
+Without requeue_pi, the glibc implementation of
+pthread_cond_broadcast() must resort to waking all the tasks waiting
+on a pthread_condvar and letting them try to sort out which task
+gets to run first in classic thundering-herd formation. An ideal
+implementation would wake the highest-priority waiter, and leave the
+rest to the natural wakeup inherent in unlocking the mutex
+associated with the condvar.
+
+Consider the simplified glibc calls:
+
+/* caller must lock mutex */
+pthread_cond_wait(cond, mutex)
+{
+ lock(cond->__data.__lock);
+ unlock(mutex);
+ do {
+ unlock(cond->__data.__lock);
+ futex_wait(cond->__data.__futex);
+ lock(cond->__data.__lock);
+ } while(...)
+ unlock(cond->__data.__lock);
+ lock(mutex);
+}
+
+pthread_cond_broadcast(cond)
+{
+ lock(cond->__data.__lock);
+ unlock(cond->__data.__lock);
+ futex_requeue(cond->data.__futex, cond->mutex);
+}
+
+Once pthread_cond_broadcast() requeues the tasks, the cond->mutex
+has waiters. Note that pthread_cond_wait() attempts to lock the
+mutex only after it has returned to user space. This will leave the
+underlying rt_mutex with waiters, and no owner, breaking the
+previously mentioned PI-boosting algorithms.
+
+In order to support PI-aware pthread_condvar's, the kernel needs to
+be able to requeue tasks to PI futexes. This support implies that
+upon a successful futex_wait system call, the caller would return to
+user space already holding the PI futex. The glibc implementation
+would be modified as follows:
+
+
+/* caller must lock mutex */
+pthread_cond_wait_pi(cond, mutex)
+{
+ lock(cond->__data.__lock);
+ unlock(mutex);
+ do {
+ unlock(cond->__data.__lock);
+ futex_wait_requeue_pi(cond->__data.__futex);
+ lock(cond->__data.__lock);
+ } while(...)
+ unlock(cond->__data.__lock);
+ /* the kernel acquired the the mutex for us */
+}
+
+pthread_cond_broadcast_pi(cond)
+{
+ lock(cond->__data.__lock);
+ unlock(cond->__data.__lock);
+ futex_requeue_pi(cond->data.__futex, cond->mutex);
+}
+
+The actual glibc implementation will likely test for PI and make the
+necessary changes inside the existing calls rather than creating new
+calls for the PI cases. Similar changes are needed for
+pthread_cond_timedwait() and pthread_cond_signal().
+
+Implementation
+--------------
+
+In order to ensure the rt_mutex has an owner if it has waiters, it
+is necessary for both the requeue code, as well as the waiting code,
+to be able to acquire the rt_mutex before returning to user space.
+The requeue code cannot simply wake the waiter and leave it to
+acquire the rt_mutex as it would open a race window between the
+requeue call returning to user space and the waiter waking and
+starting to run. This is especially true in the uncontended case.
+
+The solution involves two new rt_mutex helper routines,
+rt_mutex_start_proxy_lock() and rt_mutex_finish_proxy_lock(), which
+allow the requeue code to acquire an uncontended rt_mutex on behalf
+of the waiter and to enqueue the waiter on a contended rt_mutex.
+Two new system calls provide the kernel<->user interface to
+requeue_pi: FUTEX_WAIT_REQUEUE_PI and FUTEX_REQUEUE_CMP_PI.
+
+FUTEX_WAIT_REQUEUE_PI is called by the waiter (pthread_cond_wait()
+and pthread_cond_timedwait()) to block on the initial futex and wait
+to be requeued to a PI-aware futex. The implementation is the
+result of a high-speed collision between futex_wait() and
+futex_lock_pi(), with some extra logic to check for the additional
+wake-up scenarios.
+
+FUTEX_REQUEUE_CMP_PI is called by the waker
+(pthread_cond_broadcast() and pthread_cond_signal()) to requeue and
+possibly wake the waiting tasks. Internally, this system call is
+still handled by futex_requeue (by passing requeue_pi=1). Before
+requeueing, futex_requeue() attempts to acquire the requeue target
+PI futex on behalf of the top waiter. If it can, this waiter is
+woken. futex_requeue() then proceeds to requeue the remaining
+nr_wake+nr_requeue tasks to the PI futex, calling
+rt_mutex_start_proxy_lock() prior to each requeue to prepare the
+task as a waiter on the underlying rt_mutex. It is possible that
+the lock can be acquired at this stage as well, if so, the next
+waiter is woken to finish the acquisition of the lock.
+
+FUTEX_REQUEUE_PI accepts nr_wake and nr_requeue as arguments, but
+their sum is all that really matters. futex_requeue() will wake or
+requeue up to nr_wake + nr_requeue tasks. It will wake only as many
+tasks as it can acquire the lock for, which in the majority of cases
+should be 0 as good programming practice dictates that the caller of
+either pthread_cond_broadcast() or pthread_cond_signal() acquire the
+mutex prior to making the call. FUTEX_REQUEUE_PI requires that
+nr_wake=1. nr_requeue should be INT_MAX for broadcast and 0 for
+signal.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index fd5cac013037..4a3c2209a124 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -56,7 +56,6 @@ parameter is applicable:
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
- KMEMTRACE kmemtrace is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
LOOP Loopback device support is enabled.
@@ -329,11 +328,6 @@ and is between 256 and 4096 characters. It is defined in the file
flushed before they will be reused, which
is a lot of faster
- amd_iommu_size= [HW,X86-64]
- Define the size of the aperture for the AMD IOMMU
- driver. Possible values are:
- '32M', '64M' (default), '128M', '256M', '512M', '1G'
-
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: <a>,<b>
@@ -646,6 +640,13 @@ and is between 256 and 4096 characters. It is defined in the file
DMA-API debugging code disables itself because the
architectural default is too low.
+ dma_debug_driver=<driver_name>
+ With this option the DMA-API debugging driver
+ filter feature can be enabled at boot time. Just
+ pass the driver to filter for as the parameter.
+ The filter can be disabled or changed to another
+ driver later using sysfs.
+
dscc4.setup= [NET]
dtc3181e= [HW,SCSI]
@@ -752,12 +753,25 @@ and is between 256 and 4096 characters. It is defined in the file
ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
ftrace=[tracer]
- [ftrace] will set and start the specified tracer
+ [FTRACE] will set and start the specified tracer
as early as possible in order to facilitate early
boot debugging.
ftrace_dump_on_oops
- [ftrace] will dump the trace buffers on oops.
+ [FTRACE] will dump the trace buffers on oops.
+
+ ftrace_filter=[function-list]
+ [FTRACE] Limit the functions traced by the function
+ tracer at boot up. function-list is a comma separated
+ list of functions. This list can be changed at run
+ time by the set_ftrace_filter file in the debugfs
+ tracing directory.
+
+ ftrace_notrace=[function-list]
+ [FTRACE] Do not trace the functions specified in
+ function-list. This list can be changed at run time
+ by the set_ftrace_notrace file in the debugfs
+ tracing directory.
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
@@ -1054,15 +1068,6 @@ and is between 256 and 4096 characters. It is defined in the file
use the HighMem zone if it exists, and the Normal
zone if it does not.
- kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
- Controls whether kmemtrace is enabled
- at boot-time.
-
- kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
- subbufs kmemtrace's relay channel has. Set this
- higher than default (KMEMTRACE_N_SUBBUFS in code) if
- you experience buffer overruns.
-
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
(only serial suported for now)
@@ -1575,6 +1580,9 @@ and is between 256 and 4096 characters. It is defined in the file
noinitrd [RAM] Tells the kernel not to load any configured
initial RAM disk.
+ nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
+ remapping.
+
nointroute [IA-64]
nojitter [IA64] Disables jitter checking for ITC timers.
@@ -1660,6 +1668,14 @@ and is between 256 and 4096 characters. It is defined in the file
oprofile.timer= [HW]
Use timer interrupt instead of performance counters
+ oprofile.cpu_type= Force an oprofile cpu type
+ This might be useful if you have an older oprofile
+ userland or if you want common events.
+ Format: { archperfmon }
+ archperfmon: [X86] Force use of architectural
+ perfmon on Intel CPUs instead of the
+ CPU specific event set.
+
osst= [HW,SCSI] SCSI Tape Driver
Format: <buffer_size>,<write_threshold>
See also Documentation/scsi/st.txt.
diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index f5b7127f54ac..7f5809eddee6 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -31,6 +31,7 @@ Contents:
- Locking functions.
- Interrupt disabling functions.
+ - Sleep and wake-up functions.
- Miscellaneous functions.
(*) Inter-CPU locking barrier effects.
@@ -1217,6 +1218,132 @@ barriers are required in such a situation, they must be provided from some
other means.
+SLEEP AND WAKE-UP FUNCTIONS
+---------------------------
+
+Sleeping and waking on an event flagged in global data can be viewed as an
+interaction between two pieces of data: the task state of the task waiting for
+the event and the global data used to indicate the event. To make sure that
+these appear to happen in the right order, the primitives to begin the process
+of going to sleep, and the primitives to initiate a wake up imply certain
+barriers.
+
+Firstly, the sleeper normally follows something like this sequence of events:
+
+ for (;;) {
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ if (event_indicated)
+ break;
+ schedule();
+ }
+
+A general memory barrier is interpolated automatically by set_current_state()
+after it has altered the task state:
+
+ CPU 1
+ ===============================
+ set_current_state();
+ set_mb();
+ STORE current->state
+ <general barrier>
+ LOAD event_indicated
+
+set_current_state() may be wrapped by:
+
+ prepare_to_wait();
+ prepare_to_wait_exclusive();
+
+which therefore also imply a general memory barrier after setting the state.
+The whole sequence above is available in various canned forms, all of which
+interpolate the memory barrier in the right place:
+
+ wait_event();
+ wait_event_interruptible();
+ wait_event_interruptible_exclusive();
+ wait_event_interruptible_timeout();
+ wait_event_killable();
+ wait_event_timeout();
+ wait_on_bit();
+ wait_on_bit_lock();
+
+
+Secondly, code that performs a wake up normally follows something like this:
+
+ event_indicated = 1;
+ wake_up(&event_wait_queue);
+
+or:
+
+ event_indicated = 1;
+ wake_up_process(event_daemon);
+
+A write memory barrier is implied by wake_up() and co. if and only if they wake
+something up. The barrier occurs before the task state is cleared, and so sits
+between the STORE to indicate the event and the STORE to set TASK_RUNNING:
+
+ CPU 1 CPU 2
+ =============================== ===============================
+ set_current_state(); STORE event_indicated
+ set_mb(); wake_up();
+ STORE current->state <write barrier>
+ <general barrier> STORE current->state
+ LOAD event_indicated
+
+The available waker functions include:
+
+ complete();
+ wake_up();
+ wake_up_all();
+ wake_up_bit();
+ wake_up_interruptible();
+ wake_up_interruptible_all();
+ wake_up_interruptible_nr();
+ wake_up_interruptible_poll();
+ wake_up_interruptible_sync();
+ wake_up_interruptible_sync_poll();
+ wake_up_locked();
+ wake_up_locked_poll();
+ wake_up_nr();
+ wake_up_poll();
+ wake_up_process();
+
+
+[!] Note that the memory barriers implied by the sleeper and the waker do _not_
+order multiple stores before the wake-up with respect to loads of those stored
+values after the sleeper has called set_current_state(). For instance, if the
+sleeper does:
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (event_indicated)
+ break;
+ __set_current_state(TASK_RUNNING);
+ do_something(my_data);
+
+and the waker does:
+
+ my_data = value;
+ event_indicated = 1;
+ wake_up(&event_wait_queue);
+
+there's no guarantee that the change to event_indicated will be perceived by
+the sleeper as coming after the change to my_data. In such a circumstance, the
+code on both sides must interpolate its own memory barriers between the
+separate data accesses. Thus the above sleeper ought to do:
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (event_indicated) {
+ smp_rmb();
+ do_something(my_data);
+ }
+
+and the waker should do:
+
+ my_data = value;
+ smp_wmb();
+ event_indicated = 1;
+ wake_up(&event_wait_queue);
+
+
MISCELLANEOUS FUNCTIONS
-----------------------
@@ -1366,7 +1493,7 @@ WHERE ARE MEMORY BARRIERS NEEDED?
Under normal operation, memory operation reordering is generally not going to
be a problem as a single-threaded linear piece of code will still appear to
-work correctly, even if it's in an SMP kernel. There are, however, three
+work correctly, even if it's in an SMP kernel. There are, however, four
circumstances in which reordering definitely _could_ be a problem:
(*) Interprocessor interaction.
diff --git a/Documentation/scheduler/sched-rt-group.txt b/Documentation/scheduler/sched-rt-group.txt
index 5ba4d3fc625a..1df7f9cdab05 100644
--- a/Documentation/scheduler/sched-rt-group.txt
+++ b/Documentation/scheduler/sched-rt-group.txt
@@ -4,6 +4,7 @@
CONTENTS
========
+0. WARNING
1. Overview
1.1 The problem
1.2 The solution
@@ -14,6 +15,23 @@ CONTENTS
3. Future plans
+0. WARNING
+==========
+
+ Fiddling with these settings can result in an unstable system, the knobs are
+ root only and assumes root knows what he is doing.
+
+Most notable:
+
+ * very small values in sched_rt_period_us can result in an unstable
+ system when the period is smaller than either the available hrtimer
+ resolution, or the time it takes to handle the budget refresh itself.
+
+ * very small values in sched_rt_runtime_us can result in an unstable
+ system when the runtime is so small the system has difficulty making
+ forward progress (NOTE: the migration thread and kstopmachine both
+ are real-time processes).
+
1. Overview
===========
@@ -169,7 +187,7 @@ get their allocated time.
Implementing SCHED_EDF might take a while to complete. Priority Inheritance is
the biggest challenge as the current linux PI infrastructure is geared towards
-the limited static priority levels 0-139. With deadline scheduling you need to
+the limited static priority levels 0-99. With deadline scheduling you need to
do deadline inheritance (since priority is inversely proportional to the
deadline delta (deadline - now).
diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
new file mode 100644
index 000000000000..f157d7594ea7
--- /dev/null
+++ b/Documentation/trace/events.txt
@@ -0,0 +1,90 @@
+ Event Tracing
+
+ Documentation written by Theodore Ts'o
+ Updated by Li Zefan
+
+1. Introduction
+===============
+
+Tracepoints (see Documentation/trace/tracepoints.txt) can be used
+without creating custom kernel modules to register probe functions
+using the event tracing infrastructure.
+
+Not all tracepoints can be traced using the event tracing system;
+the kernel developer must provide code snippets which define how the
+tracing information is saved into the tracing buffer, and how the
+tracing information should be printed.
+
+2. Using Event Tracing
+======================
+
+2.1 Via the 'set_event' interface
+---------------------------------
+
+The events which are available for tracing can be found in the file
+/debug/tracing/available_events.
+
+To enable a particular event, such as 'sched_wakeup', simply echo it
+to /debug/tracing/set_event. For example:
+
+ # echo sched_wakeup >> /debug/tracing/set_event
+
+[ Note: '>>' is necessary, otherwise it will firstly disable
+ all the events. ]
+
+To disable an event, echo the event name to the set_event file prefixed
+with an exclamation point:
+
+ # echo '!sched_wakeup' >> /debug/tracing/set_event
+
+To disable all events, echo an empty line to the set_event file:
+
+ # echo > /debug/tracing/set_event
+
+To enable all events, echo '*:*' or '*:' to the set_event file:
+
+ # echo *:* > /debug/tracing/set_event
+
+The events are organized into subsystems, such as ext4, irq, sched,
+etc., and a full event name looks like this: <subsystem>:<event>. The
+subsystem name is optional, but it is displayed in the available_events
+file. All of the events in a subsystem can be specified via the syntax
+"<subsystem>:*"; for example, to enable all irq events, you can use the
+command:
+
+ # echo 'irq:*' > /debug/tracing/set_event
+
+2.2 Via the 'enable' toggle
+---------------------------
+
+The events available are also listed in /debug/tracing/events/ hierarchy
+of directories.
+
+To enable event 'sched_wakeup':
+
+ # echo 1 > /debug/tracing/events/sched/sched_wakeup/enable
+
+To disable it:
+
+ # echo 0 > /debug/tracing/events/sched/sched_wakeup/enable
+
+To enable all events in sched subsystem:
+
+ # echo 1 > /debug/tracing/events/sched/enable
+
+To eanble all events:
+
+ # echo 1 > /debug/tracing/events/enable
+
+When reading one of these enable files, there are four results:
+
+ 0 - all events this file affects are disabled
+ 1 - all events this file affects are enabled
+ X - there is a mixture of events enabled and disabled
+ ? - this file does not affect any event
+
+3. Defining an event-enabled tracepoint
+=======================================
+
+See The example provided in samples/trace_events
+
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index fd9a3e693813..2a82d8602944 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -179,7 +179,7 @@ Here is the list of current tracers that may be configured.
Function call tracer to trace all kernel functions.
- "function_graph_tracer"
+ "function_graph"
Similar to the function tracer except that the
function tracer probes the functions on their entry
@@ -518,9 +518,18 @@ priority with zero (0) being the highest priority and the nice
values starting at 100 (nice -20). Below is a quick chart to map
the kernel priority to user land priorities.
- Kernel priority: 0 to 99 ==> user RT priority 99 to 0
- Kernel priority: 100 to 139 ==> user nice -20 to 19
- Kernel priority: 140 ==> idle task priority
+ Kernel Space User Space
+ ===============================================================
+ 0(high) to 98(low) user RT priority 99(high) to 1(low)
+ with SCHED_RR or SCHED_FIFO
+ ---------------------------------------------------------------
+ 99 sched_priority is not used in scheduling
+ decisions(it must be specified as 0)
+ ---------------------------------------------------------------
+ 100(high) to 139(low) user nice -20(high) to 19(low)
+ ---------------------------------------------------------------
+ 140 idle task priority
+ ---------------------------------------------------------------
The task states are:
diff --git a/Documentation/trace/power.txt b/Documentation/trace/power.txt
new file mode 100644
index 000000000000..cd805e16dc27
--- /dev/null
+++ b/Documentation/trace/power.txt
@@ -0,0 +1,17 @@
+The power tracer collects detailed information about C-state and P-state
+transitions, instead of just looking at the high-level "average"
+information.
+
+There is a helper script found in scrips/tracing/power.pl in the kernel
+sources which can be used to parse this information and create a
+Scalable Vector Graphics (SVG) picture from the trace data.
+
+To use this tracer:
+
+ echo 0 > /sys/kernel/debug/tracing/tracing_enabled
+ echo power > /sys/kernel/debug/tracing/current_tracer
+ echo 1 > /sys/kernel/debug/tracing/tracing_enabled
+ sleep 1
+ echo 0 > /sys/kernel/debug/tracing/tracing_enabled
+ cat /sys/kernel/debug/tracing/trace | \
+ perl scripts/tracing/power.pl > out.sv
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index e0203662f9e9..8da3a795083f 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -50,6 +50,10 @@ Protocol 2.08: (Kernel 2.6.26) Added crc32 checksum and ELF format
Protocol 2.09: (Kernel 2.6.26) Added a field of 64-bit physical
pointer to single linked list of struct setup_data.
+Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
+ beyond the kernel_alignment added, new init_size and
+ pref_address fields. Added extended boot loader IDs.
+
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
@@ -168,12 +172,13 @@ Offset Proto Name Meaning
021C/4 2.00+ ramdisk_size initrd size (set by boot loader)
0220/4 2.00+ bootsect_kludge DO NOT USE - for bootsect.S use only
0224/2 2.01+ heap_end_ptr Free memory after setup end
-0226/2 N/A pad1 Unused
+0226/1 2.02+(3 ext_loader_ver Extended boot loader version
+0227/1 2.02+(3 ext_loader_type Extended boot loader ID
0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
022C/4 2.03+ ramdisk_max Highest legal initrd address
0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
-0235/1 N/A pad2 Unused
+0235/1 2.10+ min_alignment Minimum alignment, as a power of two
0236/2 N/A pad3 Unused
0238/4 2.06+ cmdline_size Maximum size of the kernel command line
023C/4 2.07+ hardware_subarch Hardware subarchitecture
@@ -182,6 +187,8 @@ Offset Proto Name Meaning
024C/4 2.08+ payload_length Length of kernel payload
0250/8 2.09+ setup_data 64-bit physical pointer to linked list
of struct setup_data
+0258/8 2.10+ pref_address Preferred loading address
+0260/4 2.10+ init_size Linear memory required during initialization
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
@@ -190,6 +197,8 @@ Offset Proto Name Meaning
field are unusable, which means the size of a bzImage kernel
cannot be determined.
+(3) Ignored, but safe to set, for boot protocols 2.02-2.09.
+
If the "HdrS" (0x53726448) magic number is not found at offset 0x202,
the boot protocol version is "old". Loading an old kernel, the
following parameters should be assumed:
@@ -343,18 +352,32 @@ Protocol: 2.00+
0xTV here, where T is an identifier for the boot loader and V is
a version number. Otherwise, enter 0xFF here.
+ For boot loader IDs above T = 0xD, write T = 0xE to this field and
+ write the extended ID minus 0x10 to the ext_loader_type field.
+ Similarly, the ext_loader_ver field can be used to provide more than
+ four bits for the bootloader version.
+
+ For example, for T = 0x15, V = 0x234, write:
+
+ type_of_loader <- 0xE4
+ ext_loader_type <- 0x05
+ ext_loader_ver <- 0x23
+
Assigned boot loader ids:
0 LILO (0x00 reserved for pre-2.00 bootloader)
1 Loadlin
2 bootsect-loader (0x20, all other values reserved)
- 3 SYSLINUX
- 4 EtherBoot
+ 3 Syslinux
+ 4 Etherboot/gPXE
5 ELILO
7 GRUB
- 8 U-BOOT
+ 8 U-Boot
9 Xen
A Gujin
B Qemu
+ C Arcturus Networks uCbootloader
+ E Extended (see ext_loader_type)
+ F Special (0xFF = undefined)
Please contact <hpa@zytor.com> if you need a bootloader ID
value assigned.
@@ -453,6 +476,35 @@ Protocol: 2.01+
Set this field to the offset (from the beginning of the real-mode
code) of the end of the setup stack/heap, minus 0x0200.
+Field name: ext_loader_ver
+Type: write (optional)
+Offset/size: 0x226/1
+Protocol: 2.02+
+
+ This field is used as an extension of the version number in the
+ type_of_loader field. The total version number is considered to be
+ (type_of_loader & 0x0f) + (ext_loader_ver << 4).
+
+ The use of this field is boot loader specific. If not written, it
+ is zero.
+
+ Kernels prior to 2.6.31 did not recognize this field, but it is safe
+ to write for protocol version 2.02 or higher.
+
+Field name: ext_loader_type
+Type: write (obligatory if (type_of_loader & 0xf0) == 0xe0)
+Offset/size: 0x227/1
+Protocol: 2.02+
+
+ This field is used as an extension of the type number in
+ type_of_loader field. If the type in type_of_loader is 0xE, then
+ the actual type is (ext_loader_type + 0x10).
+
+ This field is ignored if the type in type_of_loader is not 0xE.
+
+ Kernels prior to 2.6.31 did not recognize this field, but it is safe
+ to write for protocol version 2.02 or higher.
+
Field name: cmd_line_ptr
Type: write (obligatory)
Offset/size: 0x228/4
@@ -482,11 +534,19 @@ Protocol: 2.03+
0x37FFFFFF, you can start your ramdisk at 0x37FE0000.)
Field name: kernel_alignment
-Type: read (reloc)
+Type: read/modify (reloc)
Offset/size: 0x230/4
-Protocol: 2.05+
+Protocol: 2.05+ (read), 2.10+ (modify)
+
+ Alignment unit required by the kernel (if relocatable_kernel is
+ true.) A relocatable kernel that is loaded at an alignment
+ incompatible with the value in this field will be realigned during
+ kernel initialization.
- Alignment unit required by the kernel (if relocatable_kernel is true.)
+ Starting with protocol version 2.10, this reflects the kernel
+ alignment preferred for optimal performance; it is possible for the
+ loader to modify this field to permit a lesser alignment. See the
+ min_alignment and pref_address field below.
Field name: relocatable_kernel
Type: read (reloc)
@@ -498,6 +558,22 @@ Protocol: 2.05+
After loading, the boot loader must set the code32_start field to
point to the loaded code, or to a boot loader hook.
+Field name: min_alignment
+Type: read (reloc)
+Offset/size: 0x235/1
+Protocol: 2.10+
+
+ This field, if nonzero, indicates as a power of two the minimum
+ alignment required, as opposed to preferred, by the kernel to boot.
+ If a boot loader makes use of this field, it should update the
+ kernel_alignment field with the alignment unit desired; typically:
+
+ kernel_alignment = 1 << min_alignment
+
+ There may be a considerable performance cost with an excessively
+ misaligned kernel. Therefore, a loader should typically try each
+ power-of-two alignment from kernel_alignment down to this alignment.
+
Field name: cmdline_size
Type: read
Offset/size: 0x238/4
@@ -582,6 +658,36 @@ Protocol: 2.09+
sure to consider the case where the linked list already contains
entries.
+Field name: pref_address
+Type: read (reloc)
+Offset/size: 0x258/8
+Protocol: 2.10+
+
+ This field, if nonzero, represents a preferred load address for the
+ kernel. A relocating bootloader should attempt to load at this
+ address if possible.
+
+ A non-relocatable kernel will unconditionally move itself and to run
+ at this address.
+
+Field name: init_size
+Type: read
+Offset/size: 0x25c/4
+
+ This field indicates the amount of linear contiguous memory starting
+ at the kernel runtime start address that the kernel needs before it
+ is capable of examining its memory map. This is not the same thing
+ as the total amount of memory the kernel needs to boot, but it can
+ be used by a relocating boot loader to help select a safe load
+ address for the kernel.
+
+ The kernel runtime start address is determined by the following algorithm:
+
+ if (relocatable_kernel)
+ runtime_start = align_up(load_address, kernel_alignment)
+ else
+ runtime_start = pref_address
+
**** THE IMAGE CHECKSUM
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index 34c13040a718..2db5893d6c97 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -150,11 +150,6 @@ NUMA
Otherwise, the remaining system RAM is allocated to an
additional node.
- numa=hotadd=percent
- Only allow hotadd memory to preallocate page structures upto
- percent of already available memory.
- numa=hotadd=0 will disable hotadd memory.
-
ACPI
acpi=off Don't enable ACPI
diff --git a/Documentation/x86/x86_64/mm.txt b/Documentation/x86/x86_64/mm.txt
index 29b52b14d0b4..d6498e3cd713 100644
--- a/Documentation/x86/x86_64/mm.txt
+++ b/Documentation/x86/x86_64/mm.txt
@@ -6,10 +6,11 @@ Virtual memory map with 4 level page tables:
0000000000000000 - 00007fffffffffff (=47 bits) user space, different per mm
hole caused by [48:63] sign extension
ffff800000000000 - ffff80ffffffffff (=40 bits) guard hole
-ffff880000000000 - ffffc0ffffffffff (=57 TB) direct mapping of all phys. memory
-ffffc10000000000 - ffffc1ffffffffff (=40 bits) hole
-ffffc20000000000 - ffffe1ffffffffff (=45 bits) vmalloc/ioremap space
-ffffe20000000000 - ffffe2ffffffffff (=40 bits) virtual memory map (1TB)
+ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
+ffffc80000000000 - ffffc8ffffffffff (=40 bits) hole
+ffffc90000000000 - ffffe8ffffffffff (=45 bits) vmalloc/ioremap space
+ffffe90000000000 - ffffe9ffffffffff (=40 bits) hole
+ffffea0000000000 - ffffeaffffffffff (=40 bits) virtual memory map (1TB)
... unused hole ...
ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, from phys 0
ffffffffa0000000 - fffffffffff00000 (=1536 MB) module mapping space