qemu_boot requires xz-compressed images to live in /tmp

[umlaeute]

i'm just starting with CustomPiOS, and i'm a bit stumped on how to use qemu_boot.

1. no help or whatsoever
   it would be really nice if starting qemu_boot.sh without any arguments (or with -h; or with a non-existing file) to output some usage information
2. it apparently requires the image to be passed either as ZIP-compressed archive or an XZ-compressed image - why is it not possible to use a raw (uncompressed) image, such as created by build_dist
3. when using a ZIP-compressed archive the image has to be the first entry in the archive (I don't know whether this is also a requirement by rpi-imager, but it would be nice to have this documented)
4. when using an XZ-compressed image, it must live in /tmp otherwise the uncompressed image won't be found

[umlaeute]

also, from checking the code it seems that the image-name (unless it is a zip-file) must not contain the sequence xz preceded by an arbitrary character:

CustomPiOS/src/qemu_boot.sh

Line 15 in f6fea14

IMG_NAME=$(echo $(basename $ZIP_IMG) | sed "s/.xz//")

e.g.

$ echo mixzap.img.xz | sed "s/.xz//"
map.img.xz
$

the correct sed-expression would be "s/\.xz$//", but i think a much better way would be to use POSIX parameter expansion:

IMG_NAME=$(basename "${ZIP_IMG%.xz}")

[guysoft]

Hey, you are quite right. I initially wrote qemu_boot as a quick hack and it really has the place to become something more useful and well documented.
I am not sure how much time I have to do that now. Perhaps adding an if args<0 and to print help would be a good start. I would really welcome a PR if you have time for that.

[umlaeute]

i might :-)

sidenote: shouldn't qemu_boot.sh and qemu_boot64.sh be virtually identical (obviously apart from the CPU/kernel/dtb/...)?

[guysoft]

i might :-)

sidenote: shouldn't qemu_boot.sh and qemu_boot64.sh be virtually identical (obviously apart from the CPU/kernel/dtb/...)?

Yes, though I update which kernel is used since they changed over time. They could be joined in to one script

[umlaeute]

i found https://github.com/bablokb/pi-qemu-helper which seems to be a better alternative to your scripts (as it also supports booting with a GUI)

[guysoft]

Cool - if you have some example of what commands to run on a .zip file to get a running emulation we could add that to the wiki.
Also I am interested too :)