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Date: Tue, 20 Nov 2012 14:37:07 +0100
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [PATCH 2/2] Add AT24Cxx I2C EEPROM device model
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>

On 2012-11-20 14:27, Stefan Hajnoczi wrote:
> On Mon, Nov 19, 2012 at 03:24:39PM +0100, Jan Kiszka wrote:
>> +static void at24_flush_transfer_buffer(AT24State *s)
>> +{
>> +    if (s->cached_sector < 0 || !s->cache_dirty) {
>> +        return;
>> +    }
>> +    bdrv_write(s->bs, s->cached_sector, s->sector_buffer, 1);
> [...]
>> +static int at24_cache_sector(AT24State *s, int sector)
>> +{
>> +    int ret;
>> +
>> +    if (s->cached_sector == sector) {
>> +        return 0;
>> +    }
>> +    ret = bdrv_read(s->bs, sector, s->sector_buffer, 1);
> 
> Can you use bdrv_aio_writev()/bdrv_aio_readv()?  We should avoid adding
> new synchronous block I/O.  Because it forces us to run a nested event
> loop that blocks the guest until I/O completes.

The call is synchronous as the I2C bus model is as well. How do I model
this with bdrv_aio_*?

Jan

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