Re: [PATCH 2/2] hw/arm/armv7m: Downgrade CPU reset handler priority

[Peter Maydell]

On Thu, 27 Feb 2020 at 15:08, Stephanos Ioannidis <address@hidden> wrote:
> On 2/27/20 10:31 PM, Philippe Mathieu-Daudé wrote:
> > I think Alistair and myself use the 'loader' device with Cortex-M boards 
> > and never hit this problem.
>
> I tried both `-kernel [ELF IMAGE]` and `-device loader,file=[ELF IMAGE]` 
> without any success; in both cases, without this patch, QEMU hard-faults 
> during start-up due to the unavailability of the vector table content at the 
> time of CPU reset.

You only run into this bug if:
 * you're using a Cortex-M CPU
 * and the board model has aliased memory regions so that the
   flash or memory you're loading the ELF file into appears at
   multiple addresses in the memory map
 * and the ELF file loads the data into the aliased address
   rather than the CPU's VTOR register reset value (which is
   0 for CPUs without the Security Extension)
 * but it doesn't matter whether you use -kernel or -device loader

So you can work around it by linking your images to be loaded
at 0 rather than the higher address. It is definitely a bug
that we don't correctly handle these ELF images.

thanks
-- PMM