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From: Chuck Ebbert <>
To: Gabriel Paubert <>
Cc: linux-kernel <>
Subject: Re: [ANNOUNCE] desc.c -- dump the i386 descriptor tables
Date: Thu, 24 Apr 2003 09:59:58 -0400	[thread overview]
Message-ID: <> (raw)

Gabriel Paubert wrote:

> > #31: base=c0355600 limit=00eb flags=0089 <G=0 P=1 S=0 DPL=0 Available TSS>
> Nice but the limit field is 20 bits (shifted left by 12 bits if G=1).

  Huh.  The diagram I used was blank where the upper four limit bits belong
so I assumed it was unused... and for some reason I was thinking you
left by 16 bits when G=1, so I never noticed the missing four bits. Thanks.

> Other suggestions left as an exercise to the reader:
> a) distinguish 16 bit code from 32 bit code (GDT entry #19 is 16 bit code),


> b) distinguish read/write from read-only and execute/read from
> execute-only (are there any read-only or execute-only segments in the GDT?)
> c) distinguish 16 and 32 bit expand down data (changes the upper
> limit of the valid addresses, but it's never used in the GDT, so like
> the conformant code it's not that important)

  I now have it dumping LDTs, and should probably do at least cs:eip and
for each task.

> d) extend this for x86-64 :-)

  Itanium. 8)


             reply	other threads:[~2003-04-24 13:53 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-04-24 13:59 Chuck Ebbert [this message]
2003-04-24 16:25 ` [ANNOUNCE] desc.c -- dump the i386 descriptor tables Gabriel Paubert
  -- strict thread matches above, loose matches on Subject: below --
2003-04-24  9:06 Chuck Ebbert
2003-04-24  9:12 ` William Lee Irwin III
2003-04-24  3:02 Chuck Ebbert
2003-04-24  3:11 ` William Lee Irwin III
2003-04-24  8:53 ` Gabriel Paubert

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