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Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i38

From: Robert Millan
Subject: Re: [PATCH] access gdtdesc on segment 0 unconditionally (Re: [PATCH] i386-qemu port)
Date: Tue, 23 Jun 2009 13:02:40 +0200
User-agent: Mutt/1.5.18 (2008-05-17)

On Mon, Jun 22, 2009 at 08:53:36PM -0400, Pavel Roskin wrote:
> On Tue, 2009-06-23 at 00:43 +0200, Robert Millan wrote:
> > If I omit ADDR32 on i386-pc, I get:
> > 
> >     836f:       2e 66 0f 01 16 68 83    lgdtl  %cs:-0x7c98
> > 
> > "-0x7c98" being the signed version of 0x8368, which is also 16-bit.  What is
> > really odd is that you got 0x168 which is an offset to 0x8200, when in fact
> > %cs is 0, so I don't think your binary would work (did you test it?).
> That's because you are disassembling the linked image after relocation
> and I'm disassembling the object file.

But it's the linked image that will be executed.  The object file is only
for ld consumption (and it doesn't contain any absolute addresses, even for
instructions that require them, because link address has not yet been

Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."

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