Re: [qemu-system-aarch64] dtb flag for aarch64 Linux kernel

[Peter Maydell]

On Sat, 12 Oct 2019 at 13:30, Oleksii Kurochko
<address@hidden> wrote:
> First I successfully booted it without dtb flag in the next way:
> qemu-system-aarch64 -M virt -cpu cortex-a57 -nographic -m 2048 -kernel 
> kernel/arch/arm64/boot/Image -append "console=ttyAMA0"

Yes, this is the expected way to use the 'virt' board.

> After that I decided to dump dtb that is generated inside Qemu:
> qemu-system-aarch64 -M virt,dumpdtb=virt.dtb -cpu cortex-a57 -nographic -m 
> 2048 -kernel kernel/arch/arm64/boot/Image -append "console=ttyAMA0"
>
> Finally I tried to boot it with dumped dtb:
> qemu-system-aarch64 -M virt -cpu cortex-a57 -nographic -m 2048 -kernel 
> kernel/arch/arm64/boot/Image -append "console=ttyAMA0
> " -dtb virt.dtb
> But I did not see any messages.

Hmm. In theory that's supposed to work, but it's a bit of
an odd thing to do -- generally you just let the virt
board autogenerate the DTB and you don't need to use
the -dtb option at all. (If you do this it's important
that the options you pass to the qemu binary when you
do the dumpdtb exactly match the ones you use when you
later use the virt.dtb, but it seems like you're doing that.)

thanks
-- PMM