Re: Info on mtd partitions/possible problem with splitnslu utility
- Yes, vmlinuz is a compressed vmlinux...in fact, when you boot linux
on a non-embedded systme, the first message you see on the console is
that the kernel is being decompressed. Reviewing the make files for
the kernel build will show us what program is used for the
compression. I cannot do that here at work...
--- In firstname.lastname@example.org, "paulbart1234" <paulbart@b...>
> > - copy "vmlinuz" to offset 0x60010 of allocated array, andto 'pad'
> > store 4-byte length of "vmlinuz" @ offset 0x60000
> Because of my confusion over what the 4-byte 'length' value
> represents on this mtdblock (whether/not it includes the 16-byte
> header), I'm concerned that if a *new* 'vmlinuz' file were
> created/re-packed into the image, the 'length' value may not be
> In that case, you may want to 'pad' the length value by 12 bytes.
> But, keep in mind that if you extracted 'vmlinuz' from a .bin image
> with the assumption of the 16-byte header, then the length
> of 'vmlinuz' would be correct already (so you wouldn't want
> the length - otherwise it would 'grow' every time you
> Isn't 'vmlinuz' a compressed form of 'vmlinux'? (I remember that
> from a long time ago). If we can decompress it, we can determine
> the actual length, and know what the 4-byte 'length' value should
> - Paulb
- I believe it uses the command "bzip2". Not sure if
gzip is compatible or not.
--- joule360 <joule360@...> wrote:
> Reviewing the__________________________________
> make files for
> the kernel build will show us what program is used
> for the
> compression. I cannot do that here at work...
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- It seems that 'gzip' is used for compressing vmlinuz.
I did a Google search, and found that the hex bytes '1F 8B 08 00'
are the 'magic #' for the start of a gzip file.
I found that sequence at offset 0x2dd4 in vmlinuz (the first 0x2dd4
bytes are the boot loader that has the gunzip code to decompress
To decompress into vmlinux, skip the first 0x2dd4 (11732) bytes and
pass the rest through gunzip. Use a command like:
dd if=vmlinuz bs=1 skip=11732 | zcat > vmlinux
You should see output like:
855028+0 records in
855028+0 records out
zcat: stdin: decompression OK, trailing garbage ignored
(key is: "decompression OK" - it's OK to see the 'trailing garbage'
'vmlinux' is the decompressed kernel image - run 'strings' on it for
a quick glimpse into what's inside it.
--- In email@example.com, David Mitchell <gossiphog@y...>
> I believe it uses the command "bzip2". Not sure if
> gzip is compatible or not.
> --- joule360 <joule360@y...> wrote:
> > Reviewing the
> > make files for
> > the kernel build will show us what program is used
> > for the
> > compression. I cannot do that here at work...
> Do you Yahoo!?
> New and Improved Yahoo! Mail - Send 10MB messages!