I'm trying to use the UART for my own purposes. I'm using Raspbian
I've edited cmdline.txt and inittab but I still get the one line message
Uncompressing Linux... done, booting the kernel.
How do I stop this message from showing?
Solution: (@joan provided the answer in her link, but It needed tweaking to find the new offset, so here's how to do find the offset)
You need to uncompress kernel.img which is found in the /boot directory (raspbian). kernel.img contains a header and then gzipped data. You first need to inspect the compressed kernel and find the offset to the compressed data (A gzip header in hex is &h1f8b0800).
od -A d -t x1 /boot/kernel.img | grep '1f 8b 08 00'
This should result in a line such as:
0017360 1f 8b 08 00 00 00 00 00 02 03 e4 fd 0b 7c 54 d5
0017360 00 00 00 00 00 00 00 00 1f 8b 08 00 00 00 00 00
In the first result above, the offset is 0017360, in the second the offset is 0017360+8=0017368
Take YOUR offset and replace the 17360 below
dd if=/boot/kernel.img skip=1 bs=17360 | gzip -d >/boot/kernel_uncompressed.img
If all went to plan, the kernel is now uncompressed, you now need to replace the compressed kernel with the uncompressed one (as root) over the kernel.
cd /boot #Backup the compressed kernel cp kernel.img kernel_compressed.img #Replace the kernel cp kernel_uncompressed.img kernel.img #Reboot reboot