Re: [Qemu-devel] [PATCH 1/2] memory: Provide separate handling of unassigned io ports accesses

["Andreas Färber" <afaerber@suse.de>]

Am 09.08.2013 09:41, schrieb Paolo Bonzini:
> Il 08/08/2013 17:43, Jan Kiszka ha scritto:
>> On 2013-08-08 17:33, Peter Maydell wrote:
>>> On 3 August 2013 09:31, Jan Kiszka <jan.kiszka@web.de> wrote:
>>>> --- a/ioport.c
>>>> +++ b/ioport.c
>>>> @@ -44,6 +44,22 @@ typedef struct MemoryRegionPortioList {
>>>>      MemoryRegionPortio ports[];
>>>>  } MemoryRegionPortioList;
>>>>
>>>> +static uint64_t unassigned_io_read(void *opaque, hwaddr addr, unsigned size)
>>>> +{
>>>> +    return -1UL;
>>>
>>> This should probably be "-1ULL", otherwise we'll return
>>> different values on 32 bit and 64 bit hosts. (Actually
>>> managing a 64 bit read of the i/o space is pretty
>>> unlikely, though possibly alpha memory-mapped via the
>>> PCI space might let you do it.)
>>
>> No problem with changing this - but wouldn't 64-bit i/o accesses be a
>> bug? It's not allowed according to PCI, no device can handle it
>> (officially), so no arch should forward such requests from mmio, rather
>> break them up first.
> 
> Yes, the impl.max_access_size should never be 8.  Though 1ULL would be
> clearer perhaps.

Let's CC rth.

Andreas

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