[LinuxBIOS] LZMA compression of kernel image and p7zip (Carl-Daniel Hailfinger / Stefan Reinauer)

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Fri Aug 31 23:52:36 CEST 2007

Hello Liran,

On 30.08.2007 17:06, liran tal wrote:
> I have stumbled upon posts by Carl-Daniel and Stefan while trying to get
> some information why when I compile a kernel image with 7zip (LZMA)
> the kernel image doesn't load up.
> [...]
> I have been given an SDK based on Linux 2.6.10 for an embedded mips 4Kec (TI
> Avalanche series) cpu to build an image from. When I build the image
> using GZIP (standard) the kernel boots fine but when I
> choose 7ZIP support for better compression, the 'make ram_zimage' procedure
> is working successfully
> but when the image attempts to run off the device (via nfs) it writes:
>         Launching kernel decompressor.
>         Starting LZMA Uncompression Algorithm.
>         Compressed file is LZMA format.
>         Kernel decompressor was successful ... launching kernel.
> and nothing happens after that.

Ah, the classic "no logs available" problem because the kernel hangs
during early boot. Since it works with gzip I have to assume there is a
bug either in the decompression routine or some #define has not been
adjusted to the architecture. Less likely, but still possible would be
that the decompression routine is touching memory which is special on
your machine.

> I've been attempting to figure out what is causing the kernel not to load
> and after reading the post by Carl-Daniel and Stefan about 7zip 
> using different headers than "normal" LZMA sdk
> I thought that this could be the problem.

Possible, but rather unlikely. What do the docs for the lzma kernel
patch say? Is it supposed to be used with p7zip or the original SDK?


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