Re: [Qemu-devel] [RFC v1 2/2] arm: boot: Add EL jump-down code for Linux

[Peter Maydell]

On 2 September 2014 00:22, Peter Crosthwaite
<address@hidden> wrote:
> On Tue, Sep 2, 2014 at 9:12 AM, Peter Maydell <address@hidden> wrote:
>> Actually, I'm confused now where the reset ordering issue comes
>> in, because (ignoring realize, which will call reset) as far as I
>> could make out the only place that the ARM CPU reset gets
>> called is when the do_cpu_reset() hook in boot.c calls
>> cpu_reset(CPU(cpu)) explicitly. This is unfortunate because
>> it means if you didn't use -kernel then we won't reset the CPU
>
> Yeh, my setup fixes this via assertion of an actual CPU reset GPIO
> that connects to cpu_reset(). so I guess for me this problem is solved
> ...
>
>> if you do a system reset after first bootup...but on the other
>> hand it means there's no reset order issue?
>>
>
> ... but then the solution introduces the reset order issue for me.

Aha. (I haven't figured out how we ought to have the cpu
reset get called on system reset yet -- I was vaguely under
the impression that all QOM/qdev devices got their reset
hook called, but obviously not.)

> The other solution worth discussing now is whether we simply want to
> acknowledge that devs can have reset order deps and that's ok.
> Implementing on the qdev level:
>
> void qdev_register_reset_dep(DeviceState *dependant, Device *dependee);

I guess the question is what devices have a reset dependency
other than this odd bootloader special case? (I should try to
dig our previous discussions out of the list archives tomorrow.)

> You then QOMify the bootloader and get rid of these explicit
> bootloader cpu_reset calls.

It would certainly be nice not to have the somewhat funky
bootloader handling of reset...

-- PMM