linux-kernel - Re: [2.6.30-rc8] gcc 3.3 : _

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Message-ID: <20090605062619.GA8171@cr0.nay.redhat.com>
Date:	Fri, 5 Jun 2009 14:26:19 +0800
From:	Amerigo Wang <xiyou.wangcong@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	linux-kernel@...r.kernel.org, xiyou.wangcong@...il.com,
	andreas.herrmann3@....com, mingo@...e.hu
Subject: Re: [2.6.30-rc8] gcc 3.3 : __udivdi3 undefined.

On Thu, Jun 04, 2009 at 09:20:18PM -0700, Andrew Morton wrote:
>On Fri, 05 Jun 2009 13:00:28 +0900 Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp> wrote:
>
>> > Perhaps it's this:
>> > 
>> > static void __init memtest(u64 pattern, u64 start_phys, u64 size)
>> > {
>> > 	u64 i, count;
>> > 	u64 *start;
>> > 	u64 start_bad, last_bad;
>> > 	u64 start_phys_aligned;
>> > 	size_t incr;
>> > 
>> > 	incr = sizeof(pattern);
>> > 	start_phys_aligned = ALIGN(start_phys, incr);
>> > 	count = (size - (start_phys_aligned - start_phys))/incr;
>> Bingo!
>
>OK, thanks.  We should fix this for 2.6.30.
>
>We could do the obvious:

Excellent!


>
>--- a/arch/x86/mm/memtest.c~a
>+++ a/arch/x86/mm/memtest.c
>@@ -8,6 +8,7 @@
> #include <linux/pfn.h>
> 
> #include <asm/e820.h>
>+#include <asm/div64.h>
> 
> static u64 patterns[] __initdata = {
> 	0,
>@@ -48,7 +49,8 @@ static void __init memtest(u64 pattern, 
> 
> 	incr = sizeof(pattern);
> 	start_phys_aligned = ALIGN(start_phys, incr);
>-	count = (size - (start_phys_aligned - start_phys))/incr;
>+	count = size - (start_phys_aligned - start_phys);
>+	do_div(count, incr);
> 	start = __va(start_phys_aligned);
> 	start_bad = 0;
> 	last_bad = 0;

This patch looks fine for me. :)


>_
>
>but I wonder why all those things are u64.  They all hold virtual
>addresses, don't they?  The code doesn't test highmem.  So shouldn't
>these all be unsigned longs?
>
>

It looks like no, since many other functions also use u64 instead
of unsigned long, e.g. find_e820_area_size().

Thanks.
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