Re: [Qemu-devel] [PATCH 4/6] openpic: don't crash on a register access without a CPU context

[Alexander Graf]

On 14.12.2012, at 22:42, Scott Wood wrote:

> On 12/14/2012 06:35:12 AM, Alexander Graf wrote:
>> On 14.12.2012, at 03:12, Scott Wood wrote:
>> > If we access a register via the QEMU memory inspection commands (e.g.
>> > "xp") rather than from guest code, we won't have a CPU context.
>> > Gracefully fail to access the register in that case, rather than
>> > crashing.
>> Can't we set cpu_single_env in the debug memory access case? I'm not sure 
>> this is the only device with that problem, and by always having 
>> cpu_single_env available we would completely get rid of the whole bug 
>> category.
> 
> So, how would we go about doing this?  cpu_single_env is declared as 
> thread-local storage.  Even if there's some way to deliberately inspect a 
> different thread's local storage, I don't see how you'd get it to work 
> automatically without changing all those drivers (and are there really that 
> many that care about the CPU?) -- and we might break other places that 
> already check whether cpu_single_env is NULL.
> 
> FWIW, hw/pc.c does pretty much the same thing as this patch in 
> cpu_get_current_apic().

Ok, convinced :). Patch applied to ppc-next. Thanks ;)


Alex