-dtb option searches instead of using a file in the current directory

[Michael Hope]

If you try to run a KVM style guest using:

qemu-system-arm -M vexpress-a15 -drive file=guest.img,if=sd,cache=writeback -nographic -append 'root=/dev/mmcblk0p2 rw console=ttyAMA0 rootwait' -dtb *.dtb -kernel vmlinuz* -initrd initrd*

then qemu fails with:

Couldn't open dtb file rtsm_ve-cortex_a15x2.dtb

strace shows that QEMU tries to open /usr/share/qemu/rtsm_ve-cortex_a15x2.dtb instead of the one in the current directory. This is inconsistent with how the kernel and initrd are found. Adding a './*.dtb' works around the problem.

[Peter Maydell (pmaydell)]

Yes, it's inconsistent with -kernel and -initrd, but it's consistent with how other existing QEMU targets look for dtb files, which is why it ended up this way for ARM too.

[Peter Maydell (pmaydell)]

I've submitted the following patch which fixes this:
http://patchwork.ozlabs.org/patch/161324/
but since it also changes the filename lookup behaviour for a lot of other files it's possible it might run into resistance. We'll see.

[Peter Maydell (pmaydell)]

This patch was accepted upstream and has now made its way into qemu-linaro git; it will be in 2012.08.