* Re: [PATCH] x86_64: x86_64 version of the smp alternative patch.
[not found] <200606261900.k5QJ0k9J028243@hera.kernel.org>
@ 2006-06-27 17:57 ` Dave Jones
2006-06-28 7:54 ` Gerd Hoffmann
0 siblings, 1 reply; 2+ messages in thread
From: Dave Jones @ 2006-06-27 17:57 UTC (permalink / raw)
To: Linux Kernel Mailing List; +Cc: Gerd Hoffmann, Andi Kleen, Linus Torvalds
On Mon, Jun 26, 2006 at 07:00:46PM +0000, Linux Kernel wrote:
> commit d167a51877e94dda73dd656c51f363502309f713
> tree eb02c2974b61777f575dfdc07d4c2adf83bde434
> parent 240cd6a80642da528bfa382ec2ae4e3cb8991ea7
> author Gerd Hoffmann <kraxel@suse.de> Mon, 26 Jun 2006 13:56:16 +0200
> committer Linus Torvalds <torvalds@g5.osdl.org> Tue, 27 Jun 2006 00:48:14 -0700
>
> [PATCH] x86_64: x86_64 version of the smp alternative patch.
>
> Changes are largely identical to the i386 version:
>
> * alternative #define are moved to the new alternative.h file.
> * one new elf section with pointers to the lock prefixes which can be
> nop'ed out for non-smp.
> * two new elf sections simliar to the "classic" alternatives to
> replace SMP code with simpler UP code.
> * fixup headers to use alternative.h instead of defining their own
> LOCK / LOCK_PREFIX macros.
>
> The patch reuses the i386 version of the alternatives code to avoid code
> duplication. The code in alternatives.c was shuffled around a bit to
> reduce the number of #ifdefs needed. It also got some tweaks needed for
> x86_64 (vsyscall page handling) and new features (noreplacement option
> which was x86_64 only up to now). Debug printk's are changed from
> compile-time to runtime.
This has one behaviour slightly different to the i386 version however.
If you boot an SMP machine it does this..
SMP: Allowing 4 CPUs, 2 hotplug CPUs
Initializing CPU#0
CPU: Physical Processor ID: 0
CPU: Processor Core ID: 0
CPU0: Thermal monitoring enabled (TM1)
SMP alternatives: switching to UP code
..
SMP alternatives: switching to SMP code
Booting processor 1/2 APIC 0x1
Initializing CPU#1
Seems wasteful (and noisy) to be doing this twice during boot.
Dave
--
http://www.codemonkey.org.uk
^ permalink raw reply [flat|nested] 2+ messages in thread