Messages in this thread | | | Date | Sun, 15 Nov 1998 23:13:55 +0100 (MET) | From | Cyrille Chepelov <> | Subject | Re: i386 boot & mm gurus' advice needed (int 0x15/0xE820 support) |
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On Sun, 15 Nov 1998, Martin Mares wrote:
> It might be better to use one kbyte from PARAM+1024 as it's guaranteed > to be free (see Documentation/i386/zero-page.txt).
Huh ?
From Documentation/i386/zero-page.txt : 0x224 unsigned short setup.S heap end pointer 0x226 - 0x7ff setup.S code.
0x800 string, 256bytes COMMAND_LINE, the kernel commandline as copied using CL_OFFSET. Note: this will be copied once more by setup.c into a local buffer which is only 256 bytes long. ( #define COMMAND_LINE_SIZE 256 ) --------------- (my patched version, of course, but that applies only to the length of whatever is at 0x800)
I actually tried the place at 0x400 -- it did froze at boot (wonder why :-))
(actually, I tried first, at random, 0x400. First I retrieved only one entry, was happy. Then tried more. Froze everything. Was puzzled until I found out about Doc/zero-page ;-) )
I also tried in a subsequent version of my page to use memory at 0xc00, but stepped back, as strange problems struck me (it *might* be that egcs compiles : #define TOTO ((PARAM + 2048 + 1024 + 4)) ... stuff[TOTO] = foo;
differently (correct) than when TOTO is defined to be (PARAM + 3076). Or perhaps (more probable) that there's something else, undocumented, in the last bits of the zero page.
I'll investigate that a bit later, if no one does before me. That QSAM patch is not really necessary for 2.2 (unless it is felt that systems with a RAM hole at 14-16 Mb or whatever else need something to fix -- in which case my patch, with its zero-page mysteries solved, fits perfectly the bill).
-- Cyrille
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