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Date: Thu, 19 Feb 2009 18:14:28 +0200
From: Uri Lublin <uril@redhat.com>
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Subject: Re: [Qemu-devel] migration: adding migration to/from a file (v2)
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To: qemu-devel@nongnu.org

Anthony Liguori wrote:
> Uri Lublin wrote:
>>
>> Migration to file, uses migration-to-fd (supports live migration).
>> Migration from file, uses qemu-fopen directly.
> 
> Eh?  Haven't we already talked about why this doesn't work?  Maybe 
> there's a v3 that you meant to send?
> 

Actually I do have a v3 which uses posix-aio-compat.c
It's a much more complicated solution then just writing to a file though.
Also I am not sure if I need to use a signal or not as the migration (to-fd) 
code is polling. And if I use signal should I use SIGUSR2 or a different one and 
use a pipe similar to block-raw-posix.c ?

Your concern in the previous patch was that write() to a regular file might 
block. That's why I'm calling select before calling write. Do you think select 
will mark the fd as writeable but write would still block ?

Thanks,
     Uri.