Re: [MiNT] [PATCH] Make EHCI driver interrupt handler follow PCI-BIOS specification.

[David Gálvez <dgalvez75@gmail.com>]

2014-10-08 14:08 GMT+02:00 Vincent Rivière <vincent.riviere@freesbee.fr>:
> On 08/10/2014 11:44, David Gálvez wrote:
>>
>> +       asm volatile("move.l d1,-(SP)\n\t" : : : );
>
>
> I'm really not sure that this block does what you think (and I'm pretty sure
> it does not).
> By doing so, you modify SP, but GCC does not know that. Afterwards, it may
> access local variables or parameters through SP. If you change SP, those
> references will be wrong.
>
> The only safe way to preserve registers in a callback is to implement it as
> a full assembler stub (in a .S file). So it can save/restore the registers,
> get the parameters and call a standard C function containing the main
> callback code.
>


Thanks Vincent for taking a look to the patch and also for the advice,
I'll review it.
The code has been tested and it's working but I understand that could
be just luck.