Booting Pocketbook in qemu

[sigizmund]

Hey folks,

I've been hacking my Touch Lux 4 lately - mainly trying to boot full system image in qemu.

Here's what I am doing:

1. I made full image of the internal SD card
2. Figured out that partition #7 is the root partition (with /sbin/init)

Now I am running:

qemu-system-arm -M vexpress-a9 -kernel vmlinuz-3.2.0-4-vexpress -initrd initrd.img-3.2.0-4-vexpress -sd ../full_disk.raw -append "ext2=1 root=/dev/mmcblk0p7"

Note, that I am not immediately certain that vexpress-a9 is the right machine type, but this page suggests this is a good option for Allwiner A10 (sun5i) CPU in my Pocketbook.

I figured that I have to pass ext2=1 to kernel command line because otherwise it fails to mount the partition (idk why ext2 is not enabled by default in initrd).

So right now the process goes all the way to running init which fails:

/init: line 327: can't open /root/dev/console: no such file

and panic ensues.

Any thoughts how can I make progress there?

[WaseemAlkurdi]

You must add:

 ... console=ttyAMA0

to your QEMU commandline.

[sigizmund]

Originally Posted by WaseemAlkurdi

You must add:

 ... console=ttyAMA0

to your QEMU commandline.

Thanks! Now I am running:

qemu-system-arm -M vexpress-a9 -kernel vmlinuz-3.2.0-4-vexpress -initrd initrd.img-3.2.0-4-vexpress -sd ../full_disk.qcow2 -append "ext2=1 root=/dev/mmcblk0p7 console=ttyS0"

However, the qemu screen is now empty and no messages are printed in the console other than:

sgzmd@roman-dev:qemu/sunxi]$ qemu-system-arm -M vexpress-a9 -kernel vmlinuz-3.2.0-4-vexpress -initrd initrd.img-3.2.0-4-vexpress -sd ../full_disk.qcow2 -append "ext2=1 root=/dev/mmcblk0p7 console=ttyS0"                     
pulseaudio: set_sink_input_volume() failed
                                          pulseaudio: Reason: Invalid argument
                                                                              pulseaudio: set_sink_input_mute() failed
                                                                                                                      pulseaudio: Reason: Invalid argument

Since the qemu screen empty I can't really see what's the next problem. Using -curses option doesn't help - grey screen and nothing much else.

Also Ctrl-C' no longer works (expected?)

[sigizmund]

Also, changing to console=ttyAMA0 produces identical result, that was just me playing. Not sure what's the difference to be completely honest.

[ezdiy]

The monitor app won't boot in qemu as it expects a lot of I/O specific to this board it assumes to be present. Moreoever, real system uses multiple partitions you need to expose as mmc layout correctly - best is to just give it full NAND dump and let qemu expose that as full emmc device. A good starting point is to look at what the running system actually does and try to replicate that.

And even after that, you'll have to then manually patch monitor.app to ignore all the missing ioctls. In summary, it's not usually worth it. Its usually far simpler AND more useful (able to trace actual kernel) on a running system directly, on the device. Like most allwinner boards, it's neigh impossible to truly brick your system, even if you do something exceptionally silly, like wipe out whole emmc. The brom is smart enough to fallback to secondary mmc.

Just make sure to do the important part: Have full dump of the stock emmc at hand, to have something you can restore. Official FW update files *cannot* really repair broken partitions on their own.

[sigizmund]

Originally Posted by ezdiy

Its usually far simpler AND more useful (able to trace actual kernel) on a running system directly, on the device. Like most allwinner boards, it's neigh impossible to truly brick your system, even if you do something exceptionally silly, like wipe out whole emmc. The brom is smart enough to fallback to secondary mmc.

Just make sure to do the important part: Have full dump of the stock emmc at hand, to have something you can restore. Official FW update files *cannot* really repair broken partitions on their own.

Thanks a lot for the advice! I'll start digging that direction then!