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Date: Mon, 2 Jul 2007 13:23:03 +0300 From: "Ahmed S. Darwish" <darwish.07@...il.com> To: Andreas Schwab <schwab@...e.de> Cc: Jeremy Fitzhardinge <jeremy@...p.org>, linux-kernel@...r.kernel.org Subject: Re: [i386] Questions regarding provisional page tables initialization Hi Andreas, On Mon, Jul 02, 2007 at 11:18:08AM +0200, Andreas Schwab wrote: > "Ahmed S. Darwish" <darwish.07@...il.com> writes: > > > yes, but isn't the displacement here (0x007) a _bytes_ displacement ?. so > > effectively, %ecx now contains physical address of pg0 + 7bytes. Is it A > > meaningful place/address ?. > > It's not pg0 + 7bytes, it is pg0 plus 3 flag bits. Since a page address > is always page aligned, the low bits are reused for flags. > I'm sure there's a problem in _my_ understanding, but isn't the displacement - as specified by AT&T syntax - represented in bytes ?. I've wrote a small assembly function to be sure: .data integer: .string "%d\n" .text test_func: push %ebp mov %esp, %ebp push 0x008(%ebp) ## 8 bytes displacement (the first arg), right ? push $integer call printf mov %ebp, %esp pop %ebp ret The above method works fine and prints "5" to stdout by the code: .global main main: mov $5, %eax push %eax call test_func movl $1, %eax movl $0, %ebx int $0x80 now back to head.S code: leal 0x007(%edi),%ecx /* Create PDE entry */ Isn't the above line the same condition (bytes, not bits displacement) ?. Thanks for your patience !. (For other kind replies, don't understand me wrong. I did my homework and studied the pte format before asking ;). It's just the bytes/bits issue above that confuses me). -- Ahmed S. Darwish HomePage: http://darwish.07.googlepages.com Blog: http://darwish-07.blogspot.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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