Re: Commit 1b7898ee276b "powerpc/boot: Use the pre-boot decompression API" breaks boot

Am 10.10.2016 um 06:41 schrieb Michael Ellerman:

Heiner Kallweit [off-list ref] writes:

quoted

Am 07.10.2016 um 21:26 schrieb Heiner Kallweit:

quoted

Am 07.10.2016 um 07:51 schrieb Oliver O'Halloran:

quoted

Hi, Heiner

Could you send me a copy of the kernel .config (or which defconfig)
that you're using, the name of the HW platform that you're using and
if possible the kernel image itself?

Thanks,
Oliver

Thanks for the quick reply. Attached are .config and cuImage.
HW is a TP-Link TL-WDR4900 WiFi router (P1014-based) running OpenWRT.

After further checking I think I found the issue. The old gunzip code
handled uncompressed data transparently whilst the new one bails out
if it doesn't find a proper gzip header.
And in my case the actual kernel image is uncompressed.
With the following patch the system boots fine again (at least for me).

Thanks for testing and tracking it down.

I wonder why the actual image is uncompressed? Or alternately why do we
tell uboot the image is compressed when it's not?

Uboot is provided with a compressed image, but what gets compressed is
not the pure kernel image but the resulting image incl. boot wrapper code,
see this part of the wrapper script:

cuboot*)
    gzip -n -f -9 "$ofile"
    ${MKIMAGE} -A ppc -O linux -T kernel -C gzip -a "$base" -e "$entry" \
            $uboot_version -d "$ofile".gz "$ofile"

And this resulting image is decompressed by uboot already during boot.
Therefore the boot wrapper code sees an uncompressed kernel image.

IMHO in case of using cuboot no CONFIG_KERNEL_<COMPR TYPE> config option
should be set and Makefile + code in arch/powerpc/boot should be able
to deal with this situation:
- don't copy and build the decompression stuff
- use an alternative version of prep_kernel() in main.c which doesn't
  attempt to decompress the kernel image

This should be a cleaner solution than probing the kernel image whether
it's compressed or not.

Rgds, Heiner