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Re: [Qemu-devel] [PATCH v2 1/2] memory: Fix old portio word accesses

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH v2 1/2] memory: Fix old portio word accesses
Date: Sun, 18 Sep 2011 19:49:46 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0.2) Gecko/20110906 Thunderbird/6.0.2

On 09/18/2011 07:28 PM, Jan Kiszka wrote:
>>  This is PIO, limited by the x86 address space to 16 bit. Will add a
>>  comment.
>  x86 PIO is not limited to 16 bits, just ISA, which memory.c knows
>  nothing about.

Confused address and data, the former is limited 16, the latter can be
32 as well. But I guess only ISA models made use of the core's split up
service, and that's why QEMU limited itself accordingly.

Let's not bury such details in the core.

>>  >    Why not use access_with_adjusted_size()?
>>  Because of different accessor prototypes.
>  Can be thunked.  There is a different issue, a_w_a_s() can use small
>  accesses to emulate large ones, but not vice versa.  It needs fixing
>  anyway.

IIRC, that's a feature: Devices not implementing small accesses tend to
refuse them in reality.

I don't think this holds for pci; there the bus always generates 32-bit writes with separate byte enables for each lane. The device need not even be aware of a sub-word access, for reads.

error compiling committee.c: too many arguments to function

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