From 72548e836b0c4abbb652e791dee9c91203a9a4c6 Mon Sep 17 00:00:00 2001
From: Matt Fleming
Date: Fri, 4 Oct 2013 09:36:56 +0100
Subject: x86/efi: Add EFI framebuffer earlyprintk support

It's incredibly difficult to diagnose early EFI boot issues without
special hardware because earlyprintk=vga doesn't work on EFI systems.

Add support for writing to the EFI framebuffer, via earlyprintk=efi,
which will actually give users a chance of providing debug output.

Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Jones <pjones@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
 arch/x86/kernel/early_printk.c | 7 +++++++
 1 file changed, 7 insertions(+)

(limited to 'arch/x86/kernel')

diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index d15f575a861b..6d3d20073615 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -17,6 +17,8 @@
 #include <asm/mrst.h>
 #include <asm/pgtable.h>
 #include <linux/usb/ehci_def.h>
+#include <linux/efi.h>
+#include <asm/efi.h>
 
 /* Simple VGA output */
 #define VGABASE		(__ISA_IO_base + 0xb8000)
@@ -234,6 +236,11 @@ static int __init setup_early_printk(char *buf)
 			early_console_register(&early_hsu_console, keep);
 		}
 #endif
+#ifdef CONFIG_EARLY_PRINTK_EFI
+		if (!strncmp(buf, "efi", 3))
+			early_console_register(&early_efi_console, keep);
+#endif
+
 		buf++;
 	}
 	return 0;
-- 
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