[U-Boot] u-boot fails to uncompress a "gzip'ed -9" kernel

[N. van Bolhuis <nvbolhuis@aimvalley.nl>]

Hi Wolfgang,

thanks for your reply.


Wolfgang Denk wrote:
> Are you sure it is only an issue of gzip compression, and not for
> example of image sizes?
> 

The "gzip -8" compressed kernel, which does work, is obviously bigger
(vmlinux.bin.gz=1717766 (i.s.o. 1717544). Uncompressed size
is unchanged of course (vmlinux.bin=3646004)).

I have another "gzip -9" kernel which is smaller compressed
(vmlinux.bin.gz=1716893, vmlinux.bin=3646004). This one does work.

To be more sure I did some more tests:

I extended the working "gzip -9" kernel with dummy bytes, recompressed
it with "gzip -9" (now vmlinux.bin.gz=1717607, vmlinux.bin=3660385) and
it still works.

I added misc binary support to the problematic kernel, the resulting
image size are: vmlinux.bin.gz=1720890 vmlinux.bin=3654196. Now the
problem is gone.

I removed misc binary support from the above kernel, the
resulting image sizes are (again) vmlinux.bin.gz=1717544,
vmlinux.bin=3646004. The problem is there.


>> As far as I know my start/load memory addresses are ok.
> 
> Are you sure?
> 

no, therefore I included more details.

>> => run tird
> 
> <sarcasm>
> Excellent information. Now we all know *exactly* which commands you
> might be running :-(
> </sarcasm>
> 

tird=tftp 2000000 uImage;tftp 1000000 initramfs.igz.uboot;tftp 400000 
mpc8313erdb.dtb;bootm 2000000 1000000 400000

>> Filename 'uImage'.
>> Load address: 0x2000000
>> Loading: #################################################################
>>           #####################################################
>> done
>> Bytes transferred = 1717604 (1a3564 hex)
> ...
>> ## Booting kernel from Legacy Image at 02000000 ...
>>     Image Name:   Linux-2.6.28wa2
>>     Created:      2009-01-19  11:36:09 UTC
>>     Image Type:   PowerPC Linux Kernel Image (gzip compressed)
>>     Data Size:    1717540 Bytes =  1.6 MB
> 
> So your compressed image is 1717540 bytes or 1.64 MB...
> 
>> ## Flattened Device Tree blob at 00400000
>>     Booting using the fdt blob at 0x400000
>>     of_flat_tree at 0x00400000 size 0x00002b7a
>>     Uncompressing Kernel Image ...
> 
> And your device tree is at 4 MB. If compresses better than some 40%
> than the uncompressed size of the kernel will exceed the 4 MB limit,
> thus overwriting your device tree blob.
> 
> Are you *really* sure that your addresses are OK? What happens when
> you move the DTB to a much higher address?
> 

The uncompressed size of the kernel is 3646004 bytes. I should have
mentioned that. So vmlinux.bin.gz=1717540 and vmlinuz.bin=3646004

Notice that in my new tests (see above) the vmlinux.bin.gz ends up 4
bytes more (1717544 bytes).

If the DTB is loaded at 600000 (6M) there's no difference.

In fact, if I load no DTB nor ramdisk the same problem occurs.

Regards,
Norbert.