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Re: [Qemu-devel] armv7m/stm32f205 not starting if code linked from 0x080


From: Liviu Ionescu
Subject: Re: [Qemu-devel] armv7m/stm32f205 not starting if code linked from 0x08000000
Date: Mon, 8 Jun 2015 22:18:11 +0300

> On 08 Jun 2015, at 22:08, Peter Maydell <address@hidden> wrote:
> 
> On 8 June 2015 at 19:48, Liviu Ionescu <address@hidden> wrote:
>>> On 08 Jun 2015, at 21:36, Peter Maydell <address@hidden> wrote:
>>> 
>>> OK, so the problem diagnosis is right. I'm playing around with
>>> a patch which postpones PC/SP load until we start execution.
>> 
>> but is this really necessary?
>> 
>> the configuration at the moment cpu_reset is called is perfectly
>> stable, all memory regions are defined, the image was loaded, etc.
> 
> No, the image hasn't been loaded into RAM yet, that's why
> the ldl_phys codepath doesn't work.

aha, in this case the problem is the two step load, not the reset itself, or 
even more accurate, it is a problem of making the reset calls in the proper 
order.

> In particular, data is
> only copied into guest ram in the rom_reset() function, which
> may be and in practice is called after the arm_cpu_reset()
> function.

would it be possible to explicitly call rom_reset before arm_cpu_reset?

> What does it do if the reset vector isn't readable (ie
> reading it faults)?

I don't know, but for devices with internal flash it would be highly unlikely 
to fault, the memory is always there.


regards,

Liviu




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