Re: [Qemu-devel] vexpress-a9 aborts when booting decompress code from a modified Linux kernel

[Ilya Lipnitskiy]

On Fri, Oct 16, 2015 at 11:09 AM, Peter Maydell
<address@hidden> wrote:

> You might find it helpful to turn on QEMU's debug logging
> (see the -d and -D options). Chances are that some insn
> in your new code is faulting (probably UNDEFing).
I think have figured it out, looks like my code was doing two bad things:
1. Trying to save registers to a nonexistent stack ($sp == 0 when
stmia is called)
2. Clobbering r4 that is used globally throughout head.S

Removing the stmia/ldmia, and using r7 instead of r4 appears to have
resolved the issue.

It is a mystery how this code has been working on actual hardware, and
why reverting SHA 6ec1588e097 somehow made QEMU work. Any clues why?

Thanks for all the help!

Ilya