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SubjectRe: [PATCH v6 19/27] x86, boot: update comments about entries for 64bit image
On 12/13/2012 04:13 PM, Yinghai Lu wrote:
> On Thu, Dec 13, 2012 at 3:27 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>> On 12/13/2012 02:02 PM, Yinghai Lu wrote:
>>> + * If we come here from a bootloader, kernel(text+data+bss+brk),
>>> + * ramdisk, zero_page, command line could be above 4G.
>>> + * We depend on an identity mapped page table being provided
>>> + * that maps our entire kernel(text+data+bss+brk), and hopefully
>>> + * all of memory.
>>
>> We should make it explicit what we depend on. We certainly *can* depend
>> only on text+data+bss+brk ... with the dynamic page table approach we
>> can do that, and that would be most conservative; if we depend on other
>> things we should make that explicit, not just here but in boot.txt.
>
> yes, in my version, only need kernel(text+data+bss+brk) get mapped.
> aka the INIT_SIZE for decompressing.
>

It is definitely the minmum we can rely on, and so is the minimum we
should rely on. In fact, we don't even need .bss/.brk to be mapped, but
we probably should require that as a matter of protocol.

-hpa

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



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