No compression technique of zImage/uImage detected - ARM

Maikel Coenen maikel.coenen at
Wed Jul 24 02:13:40 PDT 2019

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
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?
Kind regards,
Maikel Coenen

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