Messages in this thread | | | Date | Thu, 13 Dec 2012 16:38:45 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH v6 19/27] x86, boot: update comments about entries for 64bit image |
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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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