linux-kernel - Re: [PATCH 1/3] x86: add lapic_shutdown for x86

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Date:	Mon, 29 Oct 2007 15:45:09 -0700
From:	Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	vgoyal@...ibm.com, hbabu@...ibm.com, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org
Subject: Re: [PATCH 1/3] x86: add lapic_shutdown for x86_64

Eric W. Biederman wrote:
> Hiroshi Shimamoto <h-shimamoto@...jp.nec.com> writes:
> 
>>> Do we really have to introduce this function for 64bit? I remember some
>>> issues were faced on i386 w.r.t kernel enabling the LAPIC against the
>>> wishes of BIOS hence kernel was disabling it while shutting down. No
>>> such problems were reported for x86_64 hence this function existed only
>>> for i386.
>> Thanks for the comment. I didn't know the issues, so I'd simply added
>> this function for unification.
>>
>>> If that is the case, probably we don't have to introduce lapic_shutdown()
>>> for x86_64. Instead call lapic_shutdown() for X86_32, and disble_local_APIC()
>>> otherwise?
>> I will do that. I was thinking which is good when posting these patches.
> 
> I'm a little concerned here.  This sounds like forced unification.
> If we can't clean up the infrastructure so things are obviously better
> and cleanly factored for both architectures we should not unify the files.
> 
> As a general principle I would rather have two crudy files side by
> side the one super crudy file.
> 
> So for unification I suggest finally fixing this right and taking the
> apics completely out of the kexec on panic path.

Thanks for the suggestion.
But it's hard for me to imagine.
I'll try to consider about it.

Thanks
Hiroshi Shimamoto
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