bzImage -> vmlinux?

Ken Moffat ken at kenmoffat.uklinux.net
Tue Jul 13 12:28:34 PDT 2004


On Tue, 13 Jul 2004, Ian Molton wrote:

>
> This isnt to do with the kernels internal libz.
>
> this is *another* libz (and some extra code), which is slightly
> modified, and 'hacked onto' the beginning of the gzipped kernel image.
> its what does the initial decompression of the kernel and relocation to
> its actual place of execution (if necessary).
>
> for x86, its complicated by the need for an extra stage of bootloader,
> or at least, used to be.
>
> The kernel has an internal (again slightly modified) zlib to support
> devices that need gzip type compression. it used to have multiple subtly
> modified zlibs until somewhere late in 2.5 where they (all?) were merged
> into one more portable form.
>

 I'll take your word on this, Ian, since you know a lot more about it
than I do.  I've already spent more time than I wanted to in trying to
decide if the uImage I created was worth playing with (all the zImage
variants have inappropriate things, I was surprised that it managed to
build at all), but basically anyome can see how the image they use was
obtained from the vmlinux if they log the output of the kernel build.
PPC seems keen on multiple objcopy steps to different formats (funny
that, building for a mac to try to understand boot/simple (hah!) it
created all manner of coff, chrp, prep, other zImages, but all recent
macs boot from vmlinux itself).

 Anyway, once my current attempt to build QT has finished, I'll have a
play with the kernel (uImage uses vmlinux.gz, not a zImage).  Odds of
10-1 that I look for new hardware afterwards, even money that it fails
to boot.

Ken
-- 
 das eine Mal als Tragödie, das andere Mal als Farce




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