linux-kernel - Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update ucode on Intel's CPU

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Message-ID: <CAE9FiQXeODfyPJmrL7reW+nHe1RXEbTKnC=DqMfpkNKYywPWSw@mail.gmail.com>
Date:	Sat, 15 Dec 2012 12:55:40 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...ux.intel.com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"linux-tip-commits@...r.kernel.org" 
	<linux-tip-commits@...r.kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update
 ucode on Intel's CPU

On Sat, Dec 15, 2012 at 11:30 AM, H. Peter Anvin <hpa@...ux.intel.com> wrote:
> What is the point of only managing 2M at a time?  Now you have to have
> more conditionals and you don't get any more memory efficiency.

We don't need to, because real_data is less than 2M, and ramdisk is about 16M.

Also if we set map too large, could have chance to cover mem hole near
1T for AMD HT system.

>
> Filling arbitrarily into the brk is not acceptable... the brk is an O(1)
> area and all brk allocations need to be reserved at compile time, so the
> overflow handling is still necessary.

if run out of BRK, we will get panic, because early_make_pgtable will return -1.

and current BRK already have 64 slop space.

BTW, did you look at smp boot problem with early_level4_pgt version?

Yinghai
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