[PATCH] ARM: add support for uncompressed uImage kernel

Alexander Stein alexander.stein at systec-electronic.com
Thu Nov 18 05:18:45 EST 2010


Hello,

On Thursday 18 November 2010, 10:10:46 Russell King - ARM Linux wrote:
> On Thu, Nov 18, 2010 at 08:38:26AM +0100, Alexander Stein wrote:
> > We only have experience with GZIP. Our compressed kernel is ~1,8MB and
> > uncompressed ~4MB.
> > On an AT91 ARM9 SoC the decompression takes about 1-2s of time. Caches
> > should be disabled, as far as I could see in decompression code.
> 
> Are you sure?  ARM9 is supposed to be ARMv4T, which is covered by this
> entry in the proc_types table:
> 
>                 .word   0x00020000              @ ARMv4T
>                 .word   0x000f0000
>                 W(b)    __armv4_mmu_cache_on
>                 W(b)    __armv4_mmu_cache_off
>                 W(b)    __armv4_mmu_cache_flush
> 
> So caches _should_ be enabled.

I'm _not_ sure. That was a long time ago and I only did a short look into the 
decompression/setup code.
After I noticed using the uncompressed kernel is much faster, I didn't 
investigate further.

Best regards,
Alexander



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