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From: Etienne Lorrain <>
To:, "H. Peter Anvin" <>
	"Eric W. Biederman" <>
Subject: Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3
Date: Tue, 6 Feb 2007 13:12:05 +0000 (GMT)	[thread overview]
Message-ID: <> (raw)

> Building real mode code with kernel binary (vmlinux) has got another
> disadvantage that it breaks using vmlinux for kdump purposes. One compiles
> the kernel binary to execute from a different address but real mode code/data
> will continue to be at virtual/physical addr 0 and kexec can not load it
> as that physical memory is not available at all. Kdump skips the real mode
> code execution.

 But that is exactly what you want and need for kdump, isn't it?
 The ELF file did not change, the program header has the last index at
address 0 that you do not want to load because you do not want to
execute the real-mode code. Load the rest and provide the 4 Kbytes
parameter page - it should work.

> I don't know much about Gujin, but advantage here seems to be that it has
> capability to load elf files and that's why the attempt to turn kernel binary
> into a compressed elf image. Why don't we then simply add an ELF header to
> bzImage and Gujin and any ELF loader including Gujin, should be able to load
> it? (As Eric had done in one of the implementations in the past?) Why to 
>create the new infrastructure?

 Because I think when a program evolves it has to get simpler to generate,
run and maintain/debug - while doing more stuff. The number of assembler
lines has to reduce because they are difficult to maintain.
 Removing a ELF header to modify the binary and stick another ELF header
is not exactly what I think simpler - a bit like linking at a fix address and
then modifying the whole set.

HPA wrote:
> Well, Gujin wants additional code too.
> Putting an ELF header on bzImage broke some bootloaders (GRUB, I believe),
> so that's not going to happen again. See the relocatable bzImage thread...

  I also refuses to load a big file at a fixed address before asking the BIOS
 for information, I only crash once the memory when I am pretty sure everything
 seems alright, interruption disabled, just before jumping to the kernel
 entry point. Cannot do that with bzImage. Cannot easily debug without
 this feature.

> Thanks
> Vivek

  Thanks for you comment.


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             reply	other threads:[~2007-02-06 13:12 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-06 13:12 Etienne Lorrain [this message]
2007-02-07  6:44 ` Vivek Goyal
  -- strict thread matches above, loose matches on Subject: below --
2007-02-11 20:49 RE : " Eric W. Biederman
2007-02-12 10:42 ` Etienne Lorrain
2007-02-12 12:29   ` Eric W. Biederman
2007-02-12 13:58     ` Etienne Lorrain
2007-02-12 14:06     ` H. Peter Anvin
2007-02-12 19:47       ` Eric W. Biederman
2007-02-08 13:10 Etienne Lorrain
2007-02-09  5:59 ` Vivek Goyal
2007-02-09 13:04   ` Etienne Lorrain
2007-02-09 19:42     ` Eric W. Biederman
2007-02-08  9:48 Etienne Lorrain
2007-02-08 11:20 ` Eric W. Biederman
2007-02-08 11:37 ` Vivek Goyal
2007-02-08 12:10   ` Eric W. Biederman
2007-02-07 14:29 Etienne Lorrain
2007-02-07 17:12 ` H. Peter Anvin
2007-02-06 17:23 Etienne Lorrain
2007-02-06 17:34 ` H. Peter Anvin
2007-02-06 18:12 ` Eric W. Biederman
2007-02-06 13:23 Etienne Lorrain
2007-02-06 12:49 Etienne Lorrain

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