No compression technique of zImage/uImage detected - ARM

Bhupesh Sharma bhsharma at
Sun Jul 28 22:02:04 PDT 2019

Hi Maikel,

I have a couple of queries (so that I can help you better). Please see 
them in-line:

On 07/24/2019 02:43 PM, Maikel Coenen wrote:
> Hi,
> I have met an issue during loading a new kernel with Kexec on an ARMv5 SoC. The kernel is a 4.19 with Gzip compression but during loading Kexec does not recognize the compression.
> If I load the new kernel and dtb with:
> kexec -l /boot/zImage -d --dtb=/boot/u-boot.dtb

Can you please show the output of the following command:
$ file /boot/zImage

Also can you please make sure that the zImage has the right gzip header 
: magic header  0x1f, 0x8b (\037 \213)

> The output is:
> Try gzip decompression.
> Try LZMA decompression.
> lzma_decompress_file: read on /boot/zImage of 65536 bytes failed
> kernel: 0xb6a68008 kernel_size: 0x494d30
> 0000000000000000-000000000fffffff (0)
> zImage header: 0x016f2818 0x00000000 0x00494d30
> zImage size 0x494d30, file size 0x494d30
> kexec_load: entry = 0x8000 flags = 0x280000
> nr_segments = 2
> segment[0].buf   = 0xb6a68008
> segment[0].bufsz = 0x494d30
> segment[0].mem   = 0x8000
> segment[0].memsz = 0x495000
> segment[1].buf   = 0x1fcf060
> segment[1].bufsz = 0x245b
> segment[1].mem   = 0x16f2000
> segment[1].memsz = 0x3000
> Looking at the debug, the function gzdirect returns “1” which indicates the kernel compression is not of gzip but I definitely use gzip. I also tested it with LZMA compression and uImage instead of zImage but all with the same outcome.
> To be complete, I use Kexec-tools 2.0.19 and zlib 1.2.11.
> Did I implement something wrong or how can I debug this further?

I don't have a armv5 hardware and my attempt to setup a qemu + buildroot 
setup for ARMv5 (926t) lead to a failure to boot the latest upstream kernel.

I will try to fix up the setup and come back with more details.
In the meanwhile if you can share the above, I can have further look at 
the same.


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