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2013-05-25ARC: lazy dcache flush broke gdb in non-aliasing configsVineet Gupta
gdbserver inserting a breakpoint ends up calling copy_user_page() for a code page. The generic version of which (non-aliasing config) didn't set the PG_arch_1 bit hence update_mmu_cache() didn't sync dcache/icache for corresponding dynamic loader code page - causing garbade to be executed. So now aliasing versions of copy_user_highpage()/clear_page() are made default. There is no significant overhead since all of special alias handling code is compiled out for non-aliasing build Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-23ARC: Brown paper bag bug in macro for checking cache colorVineet Gupta
The VM_EXEC check in update_mmu_cache() was getting optimized away because of a stupid error in definition of macro addr_not_cache_congruent() The intention was to have the equivalent of following: if (a || (1 ? b : 0)) but we ended up with following: if (a || 1 ? b : 0) And because precedence of '||' is more that that of '?', gcc was optimizing away evaluation of <a> Nasty Repercussions: 1. For non-aliasing configs it would mean some extraneous dcache flushes for non-code pages if U/K mappings were not congruent. 2. For aliasing config, some needed dcache flush for code pages might be missed if U/K mappings were congruent. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-23ARC: copy_(to|from)_user() to honor usermode-access permissionsVineet Gupta
This manifested as grep failing psuedo-randomly: -------------->8--------------------- [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ [ARCLinux]$ ip address show lo | grep inet inet 127.0.0.1/8 scope host lo -------------->8--------------------- ARC700 MMU provides fully orthogonal permission bits per page: Ur, Uw, Ux, Kr, Kw, Kx The user mode page permission templates used to have all Kernel mode access bits enabled. This caused a tricky race condition observed with uClibc buffered file read and UNIX pipes. 1. Read access to an anon mapped page in libc .bss: write-protected zero_page mapped: TLB Entry installed with Ur + K[rwx] 2. grep calls libc:getc() -> buffered read layer calls read(2) with the internal read buffer in same .bss page. The read() call is on STDIN which has been redirected to a pipe. read(2) => sys_read() => pipe_read() => copy_to_user() 3. Since page has Kernel-write permission (despite being user-mode write-protected), copy_to_user() suceeds w/o taking a MMU TLB-Miss Exception (page-fault for ARC). core-MM is unaware that kernel erroneously wrote to the reserved read-only zero-page (BUG #1) 4. Control returns to userspace which now does a write to same .bss page Since Linux MM is not aware that page has been modified by kernel, it simply reassigns a new writable zero-init page to mapping, loosing the prior write by kernel - effectively zero'ing out the libc read buffer under the hood - hence grep doesn't see right data (BUG #2) The fix is to make all kernel-mode access permissions mirror the user-mode ones. Note that the kernel still has full access to pages, when accessed directly (w/o MMU) - this fix ensures that kernel-mode access in copy_to_from() path uses the same faulting access model as for pure user accesses to keep MM fully aware of page state. The issue is peudo-random because it only shows up if the TLB entry installed in #1 is present at the time of #3. If it is evicted out, due to TLB pressure or some-such, then copy_to_user() does take a TLB Miss Exception, with a routine write-to-anon COW processing installing a fresh page for kernel writes and also usable as it is in userspace. Further the issue was dormant for so long as it depends on where the libc internal read buffer (in .bss) is mapped at runtime. If it happens to reside in file-backed data mapping of libc (in the page-aligned slack space trailing the file backed data), loader zero padding the slack space, does the early cow page replacement, setting things up at the very beginning itself. With gcc 4.8 based builds, the libc buffer got pushed out to a real anon mapping which triggers the issue. Reported-by: Anton Kolesov <akolesov@synopsys.com> Cc: <stable@vger.kernel.org> # 3.9 Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-23ARC: [mm] Prevent stray dcache lines after__sync_icache_dcach()Vineet Gupta
Flush and INVALIDATE the dcache page. This helper is only used for writeback of CODE pages to memory. So there's no value in keeping the dcache lines around. Infact it is risky as a writeback on natural eviction under pressure can cause un-needed writeback with weird issues on aliasing dcache configurations. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-10Merge tag 'arc-v3.10-rc1-part2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc Pull second set of arc arch updates from Vineet Gupta: "Aliasing VIPT dcache support for ARC I'm satisified with testing, specially with fuse which has historically given grief to VIPT arches (ARM/PARISC...)" * tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: ARC: [TB10x] Remove GENERIC_GPIO ARC: [mm] Aliasing VIPT dcache support 4/4 ARC: [mm] Aliasing VIPT dcache support 3/4 ARC: [mm] Aliasing VIPT dcache support 2/4 ARC: [mm] Aliasing VIPT dcache support 1/4 ARC: [mm] refactor the core (i|d)cache line ops loops ARC: [mm] serious bug in vaddr based icache flush
2013-05-09Merge tag 'arc-v3.10-rc1-part1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc Pull ARC port updates from Vineet Gupta: "Support for two new platforms based on ARC700: - Abilis TB10x SoC [Chritisian/Pierrick] - Simulator only System-C Model [Mischa] ARC specific MM improvements: - Avoid full TLB flush (ASID increment) on munmap (even single page) - VIPT Cache Flushing improvements + Delayed dcache flush for non-aliasing dcache (big performance boost) + icache flush aliasing agnostic (no need to kill all possible aliases) Others: - Avoid needless rebuild of DTB files for every kernel build - Remove builtin cmdline as that is already provided by DeviceTree/bootargs - Fixing unaligned access emulation corner case - checkpatch fixes [Sachin] - Various fixlets [Noam] - Minor build failures/cleanups" * tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (35 commits) ARC: [mm] Lazy D-cache flush (non aliasing VIPT) ARC: [mm] micro-optimize page size icache invalidate ARC: [mm] remove the pessimistic all-alias-invalidate icache helpers ARC: [mm] consolidate icache/dcache sync code ARC: [mm] optimise icache flush for kernel mappings ARC: [mm] optimise icache flush for user mappings ARC: [mm] optimize needless full mm TLB flush on munmap ARC: Add support for nSIM OSCI System C model ARC: [TB10x] Adapt device tree to new compatible string ARC: [TB10x] Add support for TB10x platform ARC: [TB10x] Device tree of TB100 and TB101 Development Kits ARC: Prepare interrupt code for external controllers ARC: Allow embedded arc-intc to be properly placed in DT intc hierarchy ARC: [cmdline] Don't overwrite u-boot provided bootargs ARC: [cmdline] Remove CONFIG_CMDLINE ARC: [plat-arcfpga] defconfig update ARC: unaligned access emulation broken if callee-reg dest of LD/ST ARC: unaligned access emulation error handling consolidation ARC: Debug/crash-printing Improvements ARC: fix typo with clock speed ...
2013-05-09ARC: [mm] Aliasing VIPT dcache support 4/4Vineet Gupta
Enforce congruency of userspace shared mappings Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-09ARC: [mm] Aliasing VIPT dcache support 3/4Vineet Gupta
Fix the one zillion warnings Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-09ARC: [mm] Aliasing VIPT dcache support 2/4Vineet Gupta
This is the meat of the series which prevents any dcache alias creation by always keeping the U and K mapping of a page congruent. If a mapping already exists, and other tries to access the page, prev one is flushed to physical page (wback+inv) Essentially flush_dcache_page()/copy_user_highpage() create K-mapping of a page, but try to defer flushing, unless U-mapping exist. When page is actually mapped to userspace, update_mmu_cache() flushes the K-mapping (in certain cases this can be optimised out) Additonally flush_cache_mm(), flush_cache_range(), flush_cache_page() handle the puring of stale userspace mappings on exit/munmap... flush_anon_page() handles the existing U-mapping for anon page before kernel reads it via the GUP path. Note that while not complete, this is enough to boot a simple dynamically linked Busybox based rootfs Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-09ARC: [mm] Aliasing VIPT dcache support 1/4Vineet Gupta
This preps the low level dcache flush helpers to take vaddr argument in addition to the existing paddr to properly flush the VIPT dcache Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-09ARC: [mm] refactor the core (i|d)cache line ops loopsVineet Gupta
Nothing semantical * simplify the alignement code by using & operation only * rename variables clearly as paddr Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-09ARC: [mm] serious bug in vaddr based icache flushVineet Gupta
vaddr used to index the cache was clipped from the wrong end, and thus would potentially fail to flush the correct lines. The problem was dorment for so long because up until the recent optimizations it was only used for ptrace break-point only flushes. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] Lazy D-cache flush (non aliasing VIPT)Vineet Gupta
flush_dcache_page( ) is MM hook to ensure that a page has consistent views between kernel and userspace. Thus it is called when * kernel writes to a page which at some later point could get mapped to userspace (so kernel mapping needs to be flushed-n-inv) * kernel is about to read from a page with possible userspace mappings (so userspace mappings needs to be made coherent with kernel ones) However for Non aliasing VIPT dcache, any userspace mapping will always be congruent to kernel mapping. Thus d-cache need need not be flushed at all (or delayed indefinitely). The only reason it does need to be flushed is when mapping code pages. Since icache doesn't snoop dcache, those dirty dcache lines need to be written back to memory and icache line invalidated so that icache lines fetch will get the right data. Decent gains on LMBench fork/exec/sh and File I/O micro-benchmarks. (1) FPGA @ 80 MHZ Processor, Processes - times in microseconds - smaller is better ------------------------------------------------------------------------------ Host OS Mhz null null open slct sig sig fork exec sh call I/O stat clos TCP inst hndl proc proc proc --------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 3.9-rc6-a Linux 3.9.0-r 80 4.79 8.72 66.7 116. 239. 8.39 30.4 4798 14.K 34.K 3.9-rc6-b Linux 3.9.0-r 80 4.79 8.62 65.4 111. 239. 8.35 29.0 3995 12.K 30.K 3.9-rc7-c Linux 3.9.0-r 80 4.79 9.00 66.1 106. 239. 8.61 30.4 2858 10.K 24.K ^^^^ ^^^^ ^^^ File & VM system latencies in microseconds - smaller is better ------------------------------------------------------------------------------- Host OS 0K File 10K File Mmap Prot Page 100fd Create Delete Create Delete Latency Fault Fault selct --------- ------------- ------ ------ ------ ------ ------- ----- ------- ----- 3.9-rc6-a Linux 3.9.0-r 317.8 204.2 1122.3 375.1 3522.0 4.288 20.7 126.8 3.9-rc6-b Linux 3.9.0-r 298.7 223.0 1141.6 367.8 3531.0 4.866 20.9 126.4 3.9-rc7-c Linux 3.9.0-r 278.4 179.2 862.1 339.3 3705.0 3.223 20.3 126.6 ^^^^^ ^^^^^ ^^^^^ ^^^^ (2) Customer Silicon @ 500 MHz (166 MHz mem) ------------------------------------------------------------------------------ Host OS Mhz null null open slct sig sig fork exec sh call I/O stat clos TCP inst hndl proc proc proc --------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- abilis-ba Linux 3.9.0-r 497 0.71 1.38 4.58 12.0 35.5 1.40 3.89 2070 5525 13.K abilis-ca Linux 3.9.0-r 497 0.71 1.40 4.61 11.8 35.6 1.37 3.92 1411 4317 10.K ^^^^ ^^^^ ^^^ Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] micro-optimize page size icache invalidateVineet Gupta
start address is already page aligned and size is const PAGE_SIZE, thus fixups for alignment not needed in generated code. bloat-o-meter vmlinux-mm5 vmlinux add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-32 (-32) function old new delta __inv_icache_page 82 50 -32 Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] remove the pessimistic all-alias-invalidate icache helpersVineet Gupta
No users of this code anymore - so RIP ! Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] consolidate icache/dcache sync codeVineet Gupta
Now that we have same helper used for all icache invalidates (i.e. vaddr+paddr based exact line invalidate), consolidate the open coded calls into one place. Also rename flush_icache_range_vaddr => __sync_icache_dcache Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] optimise icache flush for kernel mappingsVineet Gupta
This change continues the theme from prev commit - this time icache handling for kernel's own code modification (vmalloc: loadable modules, breakpoints for kprobes/kgdb...) flush_icache_range() calls the CDU icache helper with vaddr to enable exact line invalidate. For a true kernel-virtual mapping, the vaddr is actually virtual hence valid as index into cache. For kprobes breakpoint however, the vaddr arg is actually paddr - since that's how normal kernel is mapped in ARC memory map. This implies that CDU will use the same addr for indexing as for tag match - which is fine since kernel code would only have that "implicit" mapping and none other. This should speed up module loading significantly - specially on default ARC700 icache configurations (32k) which alias. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: [mm] optimise icache flush for user mappingsVineet Gupta
ARC icache doesn't snoop dcache thus executable pages need to be made coherent before mapping into userspace in flush_icache_page(). However ARC700 CDU (hardware cache flush module) requires both vaddr (index in cache) as well as paddr (tag match) to correctly identify a line in the VIPT cache. A typical ARC700 SoC has aliasing icache, thus the paddr only based flush_icache_page() API couldn't be implemented efficiently. It had to loop thru all possible alias indexes and perform the invalidate operation (ofcourse the cache op would only succeed at the index(es) where tag matches - typically only 1, but the cost of visiting all the cache-bins needs to paid nevertheless). Turns out however that the vaddr (along with paddr) is available in update_mmu_cache() hence better suits ARC icache flush semantics. With both vaddr+paddr, exactly one flush operation per line is done. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-05-07ARC: Respect the cpu_id passed for fetching correct cpu infoNoam Camus
Signed-off-by: Noam Camus <noamc@ezchip.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-04-29mm/arc: use common help functions to free reserved pagesJiang Liu
Use common help functions to free reserved pages. Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Acked-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-09ARC: [build] Fix warnings with CONFIG_DEBUG_SECTION_MISMATCHVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-04-09ARC: remove #ifdef-ed out include of dead headerPaul Bolle
There's no (Kconfig) macro CONFIG_BLOCK_DEV_RAM. (CONFIG_BLK_DEV_RAM does exist though.) But linux/blk.h got killed in 2005 anyway (in a patch titled "kill blk.h"), so these three lines can be removed. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-04-09ARC: Fix coding style issuesSachin Kamat
Fixes the following coding style issues as detected by checkpatch: ERROR: space required before the open parenthesis '(' ERROR: "foo * bar" should be "foo *bar" WARNING: space prohibited between function name and open parenthesis '(' WARNING: please, no spaces at the start of a line Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-04-09ARC: Use <linux/*> headers instead of <asm/*>Sachin Kamat
Silences the following checkpatch warnings: WARNING: Use #include <linux/ptrace.h> instead of <asm/ptrace.h> WARNING: Use #include <linux/kprobes.h> instead of <asm/kprobes.h> WARNING: Use #include <linux/kgdb.h> instead of <asm/kgdb.h> WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h> WARNING: Use #include <linux/cache.h> instead of <asm/cache.h> Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-04-09ARC: Remove unneeded version.h header includeSachin Kamat
version.h header file inclusion is not necessary as detected by versioncheck script. Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Don't fiddle with non-existent cachesVineet Gupta
!CONFIG_ARC_HAS_(I|D)CACHE makes Linux disable caches (assuming they exist in hardware) - mostly for debugging issues with new peripherals. However, independent of CONFIG_ARC_HAS_(I|D)CACHE, Linux also needs to handle, non-existant caches, using the information in Cache BCRs (Build Configuration Reg) Reported-by: Alexey Brodkin <abrodkin@synopsys.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Add support for ioremap_prot APIGilad Ben-Yossef
Implement ioremap_prot() to allow mapping IO memory with variable protection via TLB. Implementing this allows the /dev/mem driver to use its generic access() VMA callback, which in turn allows ptrace to examine data in memory mapped regions mapped via /dev/mem, such as Arc DCCM. The end result is that it is possible to examine values of variables placed into DCCM in user space programs via GDB. CC: Alexey Brodkin <Alexey.Brodkin@synopsys.com> CC: Noam Camus <noamc@ezchip.com> Acked-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Support for single cycle Close Coupled Mem (CCM)Vineet Gupta
* Includes mapping of CCMs in address space * Annotations to move arbitrary code/data into CCM * Moving some of the critical code/data into CCM * Runtime detection/reporting Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Boot #2: Verbose Boot reporting / feature verificationVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: SMP supportVineet Gupta
ARC common code to enable a SMP system + ISS provided SMP extensions. ARC700 natively lacks SMP support, hence some of the core features are are only enabled if SoCs have the necessary h/w pixie-dust. This includes: -Inter Processor Interrupts (IPI) -Cache coherency -load-locked/store-conditional ... The low level exception handling would be completely broken in SMP because we don't have hardware assisted stack switching. Thus a fair bit of this code is repurposing the MMU_SCRATCH reg for event handler prologues to keep them re-entrant. Many thanks to Rajeshwar Ranga for his initial "major" contributions to SMP Port (back in 2008), and to Noam Camus and Gilad Ben-Yossef for help with resurrecting that in 3.2 kernel (2012). Note that this platform code is again singleton design pattern - so multiple SMP platforms won't build at the moment - this deficiency is addressed in subsequent patches within this series. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Rajeshwar Ranga <rajeshwar.ranga@gmail.com> Cc: Noam Camus <noamc@ezchip.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com>
2013-02-15ARC: Diagnostics: show_regs() etcVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: [DeviceTree] Convert some Kconfig items to runtime valuesVineet Gupta
* mem size now runtime configured (prev CONFIG_ARC_PLAT_SDRAM_SIZE) * core cpu clk runtime configured (prev CONFIG_ARC_PLAT_CLK) Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Grant Likely <grant.likely@secretlab.ca>
2013-02-15ARC: [DeviceTree] Basic supportVineet Gupta
This is minimal infrastructure needed for devicetree work. It uses an a sample "skeleton" devicetree - embedded in kernel image - to print the board, manufacturer by parsing the top-level "compatible" string. As of now we don't need any additional "board" specific "machine_desc". TODO: support interpreting the command line as boot-loader passed dtb Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: devicetree-discuss@lists.ozlabs.org Cc: Rob Herring <rob.herring@calxeda.com> Cc: James Hogan <james.hogan@imgtec.com> Reviewed-by: Rob Herring <rob.herring@calxeda.com> Reviewed-by: James Hogan <james.hogan@imgtec.com>
2013-02-15ARC: Boot #1: low-level, setup_arch(), /proc/cpuinfo, mem initVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2013-02-15ARC: I/O and DMA MappingsVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Page Fault handlingVineet Gupta
This includes recent changes to make handler "retry" and/or "killable" The killable (early exit) logic is loosely based on how SH implements it return if SIGKILL + either of VM_FAULT_OOM or VM_FAULT_RETRY which is different from Hexagon implementation which would NOT early exit for SIGKILL + VM_FAULT_OOM + !VM_FAULT_RETRY credits: Non executable stack support from Simon Spooner Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: TLB flush HandlingVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: MMU Exception HandlingVineet Gupta
* MMU I-TLB / D-TLB Miss Exceptions - Fast Path TLB Refill Handler - slowpath TLB creation via do_page_fault() -> update_mmu_cache() * Duplicate PD Exception Handler Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: MMU Context ManagementVineet Gupta
ARC700 MMU provides for tagging TLB entries with a 8-bit ASID to avoid having to flush the TLB every task switch. It also allows for a quick way to invalidate all the TLB entries for task useful for: * COW sementics during fork() * task exit()ing Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-15ARC: Cache Flush ManagementVineet Gupta
* ARC700 has VIPT L1 Caches * Caches don't snoop and are not coherent * Given the PAGE_SIZE and Cache associativity, we don't support aliasing D$ configurations (yet), but do allow aliasing I$ configs Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-11ARC: uaccess friendsVineet Gupta
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-02-11ARC: Build system: Makefiles, Kconfig, Linker scriptVineet Gupta
Arnd in his review pointed out that arch Kconfig organisation has several deficiencies: * Build time entries for things which can be runtime extracted from DT (e.g. SDRAM size, core clk frequency..) * Not multi-platform-image-build friendly (choice .. endchoice constructs) * cpu variants support (750/770) is exclusive. The first 2 have been fixed in subsequent patches. Due to the nature of the 750 and 770, it is not possible to build for both together, w/o special runtime glue code which would hurt performance. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Sam Ravnborg <sam@ravnborg.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
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