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Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i38
From: |
Pavel Roskin |
Subject: |
Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port) |
Date: |
Mon, 22 Jun 2009 17:44:43 -0400 |
On Mon, 2009-06-22 at 23:32 +0200, Robert Millan wrote:
> On Mon, Jun 22, 2009 at 10:52:13PM +0200, Robert Millan wrote:
> > I don't think it's possible to use relative addresses
> > with this particular instruction.
>
> Uhm sorry, this was silly. Of course you can use addresses relative to a
> segment in lgdt, but this doesn't change the fact that GAS always gives
> you absolute ones.
>
> Also, I'm not sure if it's possible to use a 16-bit field in this instruction,
> it could be that the field is always 32-bit, even if it's relative to a
> segment. This dump is from the i386-pc kernel.img:
>
> 836f: 2e 67 66 0f 01 15 68 addr32 lgdtl %cs:0x8368
> 8376: 83 00 00
>
> a little-endian 0x00008368 is seen here, indicating the field is 32-bit.
But if I omit ADDR32, I get:
0000016e <real_to_prot>:
16e: fa cli
16f: 2e 66 0f 01 16 68 01 lgdtl %cs:0x168
176: 0f 20 c0 mov %cr0,%eax
The address is 16-bit.
--
Regards,
Pavel Roskin
- Re: [PATCH] swap real_to_prot() and prot_to_real() (Re: [PATCH] i386-qemu port), (continued)
- Re: [PATCH] i386-qemu port, Robert Millan, 2009/06/21
- [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/21
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Pavel Roskin, 2009/06/21
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Pavel Roskin, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port),
Pavel Roskin <=
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Pavel Roskin, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/23
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Pavel Roskin, 2009/06/22
- Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
- about Apple compiler (Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port)), Robert Millan, 2009/06/22
- Re: about Apple compiler (Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port)), Pavel Roskin, 2009/06/22
[PATCH] s/GRUB_MEMORY_MACHINE_LINK_ADDR/GRUB_KERNEL_MACHINE_LINK_ADDR/g (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22
clean patch for i386-qemu port (Re: [PATCH] i386-qemu port), Robert Millan, 2009/06/22