[Qemu-devel] Re: [PATCH 11/21] ioport: insert event_tap_ioport() to ioport_write().

[Yoshiaki Tamura]

2010/12/16 Michael S. Tsirkin <address@hidden>:
> On Thu, Dec 16, 2010 at 04:37:41PM +0900, Yoshiaki Tamura wrote:
>> 2010/11/28 Yoshiaki Tamura <address@hidden>:
>> > 2010/11/28 Michael S. Tsirkin <address@hidden>:
>> >> On Thu, Nov 25, 2010 at 03:06:50PM +0900, Yoshiaki Tamura wrote:
>> >>> Record ioport event to replay it upon failover.
>> >>>
>> >>> Signed-off-by: Yoshiaki Tamura <address@hidden>
>> >>
>> >> Interesting. This will have to be extended to support ioeventfd.
>> >> Since each eventfd is really just a binary trigger
>> >> it should be enough to read out the fd state.
>> >
>> > Haven't thought about eventfd yet.  Will try doing it in the next
>> > spin.
>>
>> Hi Michael,
>>
>> I looked into eventfd and realized it's only used with vhost now.
>
> There are patches on list to use it for block/userspace net.

Thanks.  Now I understand.
In that case, inserting an even-tap function to the following code
should be appropriate?

int event_notifier_test_and_clear(EventNotifier *e)
{
    uint64_t value;
    int r = read(e->fd, &value, sizeof(value));
    return r == sizeof(value);
}

>
>>  However, I
>> believe vhost bypass the net layer in qemu, and there is no way for Kemari to
>> detect the outputs.  To me, it doesn't make sense to extend this patch to
>> support eventfd...
>>
>> Thanks,
>>
>> Yoshi
>>
>> >
>> > Yoshi
>> >
>> >>
>> >>> ---
>> >>>  ioport.c |    2 ++
>> >>>  1 files changed, 2 insertions(+), 0 deletions(-)
>> >>>
>> >>> diff --git a/ioport.c b/ioport.c
>> >>> index aa4188a..74aebf5 100644
>> >>> --- a/ioport.c
>> >>> +++ b/ioport.c
>> >>> @@ -27,6 +27,7 @@
>> >>>
>> >>>  #include "ioport.h"
>> >>>  #include "trace.h"
>> >>> +#include "event-tap.h"
>> >>>
>> >>>  /***********************************************************/
>> >>>  /* IO Port */
>> >>> @@ -76,6 +77,7 @@ static void ioport_write(int index, uint32_t address, 
>> >>> uint32_t data)
>> >>>          default_ioport_writel
>> >>>      };
>> >>>      IOPortWriteFunc *func = ioport_write_table[index][address];
>> >>> +    event_tap_ioport(index, address, data);
>> >>>      if (!func)
>> >>>          func = default_func[index];
>> >>>      func(ioport_opaque[address], address, data);
>> >>> --
>> >>> 1.7.1.2
>> >>>
>> >>> --
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>> >
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