linux-kernel - Re: [PATCH] x86: don't compile vsmp

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Date:	Thu, 26 Feb 2009 12:44:57 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Ravikiran G Thirumalai <kiran@...lex86.org>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	shai@...lex86.org
Subject: Re: [PATCH] x86: don't compile vsmp_64 for 32bit


* Ravikiran G Thirumalai <kiran@...lex86.org> wrote:

> On Wed, Feb 25, 2009 at 09:20:50PM -0800, Yinghai Lu wrote:
> >
> >Impact: cleanup
> >
> >that is only needed when CONFIG_X86_VSMP is defined with 64bit
> >also remove dead code about PCI, because CONFIG_X86_VSMP depends on PCI
> >
> >Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> >
> 
> NAK!
> vsmp64.c is compiled unconditionally for a reason.  There are ifdefs in the
> file to avoid code compilation based on config options. is_vsmp_box() is
> needed even when CONFIG_X86_VSMP is not enabled, since distro kernels don't ship
> with CONFIG_X86_VSMP, and since is_vsmp_box() is used to determine  whether
> tsc's can be considered synced or not, this is needed.

is_vsmp_box() is always available:

> >+#ifdef CONFIG_X86_VSMP
> > extern int is_vsmp_box(void);
> >+#else
> >+static inline int is_vsmp_box(void)
> >+{
> >+	return 0;
> >+}
> >+#endif

What this patch does is it reduces the kernel's size when 
CONFIG_X86_VSMP is turned off and also makes the code arguably 
cleaner.

> In the future, I would appreciate if you copy me on 
> cleanups/changes involving vsmp64.c

That is what i did when i queued up the change. That is how you 
became aware of this commit.

	Ingo
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