Messages in this thread Patch in this message | | | Date | Sun, 17 Jun 2012 08:54:52 -0700 | From | Greg Kroah-Hartman <> | Subject | Re: 3.5 regressions related to printk changes |
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On Sun, Jun 17, 2012 at 05:09:28PM +0200, Willy Tarreau wrote: > Hi Kay, > > I was failing to get any 3.5-rc[123] kernel to boot on my dockstar (armv5). > I finally found some time today to bisect it and found that the responsible > commit was : > > From 7ff9554bb578ba02166071d2d487b7fc7d860d62 Mon Sep 17 00:00:00 2001 > From: Kay Sievers <kay@vrfy.org> > Date: Thu, 3 May 2012 02:29:13 +0200 > Subject: [PATCH] printk: convert byte-buffer to variable-length record buffer > > The symptom is that the kernel loads and hangs during early boot without > displaying anything. My config had CONFIG_EARLY_PRINTK enabled so I tried > without it again just in case it would be related, but it desperately did > not change anything, the kernel still fails to boot. > > I have tried to revert printk changes on top of 3.5-rc3 and confirm that > now the kernel properly boots. Here's the list of what I reverted for > information : > > c313af145b9bc4fb8e8e0c83b8cfc10e1b894a50 printk() - isolate KERN_CONT users from ordinary complete lines > 3ce9a7c0ac28561567fadedf1a99272e4970f740 printk() - restore prefix/timestamp printing for multi-newline str > 1fce677971e29ceaa7c569741fa9c685a7b1052a printk: add stub for prepend_timestamp() > f8450fca6ecdea38b5a882fdf6cd097e3ec8651c printk: correctly align __log_buf > 649e6ee33f73ba1c4f2492c6de9aff2254b540cb printk() - restore timestamp printing at console output > 5c5d5ca51abd728c8de3be43ffd6bb00f977bfcd printk() - do not merge continuation lines of different threads > 7f3a781d6fd81e397c3928c9af33f1fc63232db6 printk - fix compilation for CONFIG_PRINTK=n > 5fc3249068c1ed87c6fd485f42ced24132405629 kmsg: use do_div() to divide 64bit integer > c4e00daaa96d3a0786f1f4fe6456281c60ef9a16 driver-core: extend dev_printk() to pass structured data > e11fea92e13fb91c50bacca799a6131c81929986 kmsg: export printk records to the /dev/kmsg interface > 7ff9554bb578ba02166071d2d487b7fc7d860d62 printk: convert byte-buffer to variable-length record buffer > > I understand that it will be hard to troubleshoot this with that little > information :-/ > > I'm not posting the config not to pollute the list, but have it available > if needed. I haven't noticed anything seemingly related on the list, but > if you want me to test a patch or to provide more information, feel free > to suggest ! > > I'm still checking if I can spot something.
Try the patch below, which is in my set of patches to go to Linus soon and let me know if it works or not.
thanks,
greg k-h
From 6ebb017de9d59a18c3ff9648270e8f6abaa93438 Mon Sep 17 00:00:00 2001 From: Andrew Lunn <andrew@lunn.ch> Date: Tue, 5 Jun 2012 08:52:34 +0200 Subject: printk: Fix alignment of buf causing crash on ARM EABI
Commit 7ff9554bb578ba02166071d2d487b7fc7d860d62, printk: convert byte-buffer to variable-length record buffer, causes systems using EABI to crash very early in the boot cycle. The first entry in struct log is a u64, which for EABI must be 8 byte aligned.
Make use of __alignof__() so the compiler to decide the alignment, but allow it to be overridden using CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, for systems which can perform unaligned access and want to save a few bytes of space.
Tested on Orion5x and Kirkwood.
Signed-off-by: Andrew Lunn <andrew@lunn.ch> Tested-by: Stephen Warren <swarren@wwwdotorg.org> Acked-by: Stephen Warren <swarren@wwwdotorg.org> Acked-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/printk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c index 32462d2..f205c25 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -227,10 +227,10 @@ static u32 clear_idx; #define LOG_LINE_MAX 1024 /* record buffer */ -#if !defined(CONFIG_64BIT) || defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) #define LOG_ALIGN 4 #else -#define LOG_ALIGN 8 +#define LOG_ALIGN __alignof__(struct log) #endif #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); -- 1.7.10.2.565.gbd578b5
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