linux-kernel - [PATCH] [Bugfix] x86/boot/compressed: Fix serial I/O during compressed boot

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Date:	Sun,  8 Feb 2015 18:33:32 +0600
From:	Alexander Kuleshov <kuleshovmail@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Kees Cook <keescook@...omium.org>,
	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Alexander Kuleshov <kuleshovmail@...il.com>
Subject: [PATCH] [Bugfix] x86/boot/compressed: Fix serial I/O during compressed boot

Previously it used early_serial_base from the
arch/x86/boot/compressed/early_serial_console.c, and it's zero everytime,
so serial I/O didn't work/print anything in the kernel decompressing code.

Let's define early_serial_base in the arch/x86/boot/early_serial_console.c
and make it extern, so code from boot/compressed directory can use it.

Signed-off-by: Alexander Kuleshov <kuleshovmail@...il.com>
---
 arch/x86/boot/compressed/early_serial_console.c | 2 --
 arch/x86/boot/compressed/misc.c                 | 3 ++-
 arch/x86/boot/early_serial_console.c            | 2 ++
 arch/x86/boot/tty.c                             | 2 --
 4 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/x86/boot/compressed/early_serial_console.c b/arch/x86/boot/compressed/early_serial_console.c
index 261e81f..c80d915 100644
--- a/arch/x86/boot/compressed/early_serial_console.c
+++ b/arch/x86/boot/compressed/early_serial_console.c
@@ -1,5 +1,3 @@
 #include "misc.h"
 
-int early_serial_base;
-
 #include "../early_serial_console.c"
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index a950864..2bde4db 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -390,7 +390,8 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 	lines = real_mode->screen_info.orig_video_lines;
 	cols = real_mode->screen_info.orig_video_cols;
 
-	console_init();
	/* 
	 * serial i/o can be already initialized if we runned in 16-bit 
	 * real mode and didn't use 32/64-bit boot protocol.
	 */
+	if (!early_serial_base)
+		console_init();
 	debug_putstr("early console in decompress_kernel\n");
 
 	free_mem_ptr     = heap;	/* Heap */
diff --git a/arch/x86/boot/early_serial_console.c b/arch/x86/boot/early_serial_console.c
index 5df2869..af32b39 100644
--- a/arch/x86/boot/early_serial_console.c
+++ b/arch/x86/boot/early_serial_console.c
@@ -1,5 +1,7 @@
 #include "boot.h"
 
+int early_serial_base;
+
 #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
 
 #define XMTRDY          0x20
diff --git a/arch/x86/boot/tty.c b/arch/x86/boot/tty.c
index def2451..0cb0b4c 100644
--- a/arch/x86/boot/tty.c
+++ b/arch/x86/boot/tty.c
@@ -15,8 +15,6 @@
 
 #include "boot.h"
 
-int early_serial_base;
-
 #define XMTRDY          0x20
 
 #define TXR             0       /*  Transmit register (WRITE) */
-- 
2.3.0

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