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Date: Tue, 11 Dec 2012 10:02:20 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Yinghai Lu <yinghai@kernel.org>
CC: Borislav Petkov <bp@alien8.de>, "Yu, Fenghua" <fenghua.yu@intel.com>,
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Subject: Re: [tip:x86/microcode] x86/microcode_intel_early.c: Early update
 ucode on Intel's CPU
References: <3E5A0FA7E9CA944F9D5414FEC6C71220470F154E@ORSMSX105.amr.corp.intel.com> <CAE9FiQXGZYZiH3eUup2UXGWkeqKjsiHk7aMTFJO7xxFkqTpBZA@mail.gmail.com> <50C6AB63.9070008@zytor.com> <CAE9FiQX7sPLXOacoLakaJ1qC5UuSUbrX_g7N-oWmLYg5W-91UA@mail.gmail.com> <50C6D3DF.3030209@zytor.com> <CAE9FiQUiEx=p6wTC5wu_E=ih1CSBaTmw90zsc2=+xu6rMO5usg@mail.gmail.com> <20121211145716.GB8873@liondog.tnic> <CAE9FiQVByBTHwPrtYvVxv4u9QrtN1iN6GH9YaDn3dvmwv5Sg7g@mail.gmail.com> <50C763C2.5020603@zytor.com> <CAE9FiQUzHBb5SiEhfrOg7hFbuD1H1-7aXa0aTjhZ9tNqdrwGqw@mail.gmail.com> <20121211170605.GD28827@liondog.tnic> <CAE9FiQXOrH4POQESnGycSrf-7e5MhO9y1wfa7ZSEVr9TO_45ZA@mail.gmail.com>
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On 12/11/2012 09:15 AM, Yinghai Lu wrote:
> On Tue, Dec 11, 2012 at 9:06 AM, Borislav Petkov <bp@alien8.de> wrote:
>> On Tue, Dec 11, 2012 at 09:00:55AM -0800, Yinghai Lu wrote:
>>> ok, then next question is how early it should be.
>>>
>>> before early_cpu_init/early_identify_cpu
>>>
>>> or just before check_bugs/identify_cpu
>>
>> Read the code. It's in x86_64_start_kernel on 64-bit.
>>
>
> No, that is not right place. initrd could be loaded anywhere like way
> high by bootloader.
>

The more I think about it, the more I think the right answer is the one 
we have pretty stated all along: if using the 64-bit entry point it is 
the responsibility of the boot loader to make sure the kernel, the setup 
data, and the initramfs are all mapped on entry.

	-hpa
-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.