Messages in this thread |  | | Date | Sat, 11 Nov 2000 16:46:09 +0000 (GMT) | From | Tigran Aivazian <> | Subject | Re: bzImage ~ 900K with i386 test11-pre2 |
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On Sat, 11 Nov 2000, Andrea Arcangeli wrote:
> On Sat, Nov 11, 2000 at 02:51:21PM +0000, Tigran Aivazian wrote: > > Yes, Andrea, I know that paging is disabled at the point of loading the > > image but I was talking about the inability to boot (boot == complete > > booting, i.e. at least reach start_kernel()) a kernel with very large > > .data or .bss segments because of various reasons -- one of which, > > probably,is the inadequacy of those pg0 and pg1 page tables set up in > > head.S > > Ah ok, I thought you were talking about bootloader. > > About the initial pagetable setup on i386 port there's certainly a 3M limit on > the size of the kernel image, but it's trivial to enlarge it. BTW, exactly for > that kernel size limit reasons in x86-64 I defined a 40Mbyte mapping where we > currently have a 4M mapping and that's even simpler to enlarge since they're 2M > PAE like pagetables. > > Basically as far as the kernel can get loaded in memory correctly we have > no problem :) > > > (which Peter says is infinite?) or the ones on .text/.data/.bss (and what > > exactly are they?)? See my question now? > > We sure hit the 3M limit on the .bss clearing right now. >
I understand and agree with what you say except the number 4M. It is not 4M but 8M, imho. See arch/i386/kernel/head.S
/* * The page tables are initialized to only 8MB here - the final page * tables are set up later depending on memory size. */ .org 0x2000 ENTRY(pg0)
.org 0x3000 ENTRY(pg1)
/* * empty_zero_page must immediately follow the page tables ! (The * initialization loop counts until empty_zero_page) */
.org 0x4000 ENTRY(empty_zero_page)
(the comment next to pg0 in asm/pgtable.h is misleading, whilst the comment above paging_init() is plain wrong -- I sent a patch to Linus yesterday but perhaps "wrong comment" is not a critical 2.4 issue :)
Regards, Tigran
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