linux-kernel - [PATCH] get rid of ARCH_HAVE_XTIME

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Date:	Mon, 11 Dec 2006 11:52:56 +0100
From:	Eric Dumazet <dada1@...mosbay.com>
To:	Andrew Morton <akpm@...l.org>
Cc:	Andi Kleen <ak@...e.de>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH] get rid of ARCH_HAVE_XTIME_LOCK

As suggested by Andrew, we can use __attribute__((weak)) to get rid of 
ARCH_HAVE_XTIME_LOCK

Please note I compiled, and boot tested on ia32 this patch, and it seems OK.
I compiled on x86_64 and got same resulting vmlinux image.

But I suspect some tools might have problems because vmlinux have its 
first 'weak data symbol' defined. AFAIK __attribute__((weak)) was only used 
on text symbols.

# nm vmlinux | grep ' V '
c03b01c0 V xtime_lock

[PATCH] get rid of ARCH_HAVE_XTIME_LOCK

ARCH_HAVE_XTIME_LOCK is used by x86_64 arch . This arch needs to place a read 
only copy of xtime_lock into vsyscall page. This read only copy is named 
__xtime_lock, and xtime_lock is defined in arch/x86_64/kernel/vmlinux.lds.S 
as an alias. So the declaration of xtime_lock in kernel/timer.c was guarded 
by ARCH_HAVE_XTIME_LOCK define, defined to true on x86_64.

We can get same result with _attribute__((weak)) in the declaration. linker 
should do the job.

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>

View attachment "ARCH_HAVE_XTIME_LOCK.patch" of type "text/plain" (1424 bytes)