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From: Ian Campbell <>
To: "H. Peter Anvin" <>
Cc: Jeremy Fitzhardinge <>,,
	"Eric W. Biederman" <>
Subject: Re: PATCH/RFC: bzImage payload as compressed ELF file.
Date: Tue, 29 Jan 2008 20:38:32 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Tue, 2008-01-29 at 10:34 -0800, H. Peter Anvin wrote:
> Jeremy Fitzhardinge wrote:
> > H. Peter Anvin wrote:
> >> It's also easy enough to either use objdump -h or nm to extract info 
> >> from vmlinux; or for some of the simpler stuff, just parse the ELF 
> >> directly (perhaps using libelf).
> >>
> >> There is also the -R option to ld, which imports symbols from one 
> >> executable into another. 
> > 
> > Yes, I used -R, though it was necessary to generate a copy of vmlinux 
> > with a filtered symbol list to prevent collisions.  But I'm not sure any 
> > of this is necessary with Ian's approach.
> > 
> Probably isn't.  He just need the start and possibly length of the 
> payload section, which should be objdump -h or equivalently reading the 
> ELF section table.

I'm currently using "objcopy --extract-symbol -w -N \* -K input_data" to
create a .o with just the symbol I'm interested in and using -R on that.
There's also an option to add a prefix to all symbols which might be

I finessed the length issue slightly since it happens that the word
before the payload is the payload's length. I'm mulling a variety of
      * declare it compression scheme dependant. At least for gzip it
        knows when it has reached the end.
      * codify the length followed by data thing we happen to have now
      * add a length field to the header, using another 4 bytes (is
        there any pressure on the size of the header?).

I'd probably go with the later unless we are pressed for space in the

Ian Campbell

Man who falls in vat of molten optical glass makes spectacle of self.

  reply	other threads:[~2008-01-29 20:41 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-28 22:42 Ian Campbell
2008-01-28 22:54 ` Jeremy Fitzhardinge
2008-01-29  9:34   ` Ian Campbell
2008-01-29 17:54     ` Jeremy Fitzhardinge
2008-01-29 18:05       ` H. Peter Anvin
2008-01-29 18:31         ` Jeremy Fitzhardinge
2008-01-29 18:34           ` H. Peter Anvin
2008-01-29 20:38             ` Ian Campbell [this message]
2008-01-29 21:50               ` H. Peter Anvin
2008-01-29 21:55                 ` Ian Campbell
2008-01-29 22:09                   ` H. Peter Anvin
2008-01-28 23:20 ` H. Peter Anvin
2008-01-29  9:31   ` Ian Campbell
2008-02-01 13:10 ` Ingo Molnar
2008-02-01 18:05   ` H. Peter Anvin
2008-02-01 18:15     ` H. Peter Anvin

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