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Date: Thu, 11 Sep 2008 13:10:33 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [5187] Use signalfd() to work around signal/select
	race
References: <E1KdRsd-0003t8-G0@cvs.savannah.gnu.org>
	<1221149035.4145.57.camel@frecb07144>
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To: Laurent Vivier <Laurent.Vivier@bull.net>
Cc: qemu-devel@nongnu.org

Laurent Vivier wrote:
> Le mercredi 10 septembre 2008 à 15:45 +0000, Anthony Liguori a écrit :
>   
>> Revision: 5187
>>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5187
>> Author:   aliguori
>> Date:     2008-09-10 15:45:19 +0000 (Wed, 10 Sep 2008)
>>
>> Log Message:
>> -----------
>> Use signalfd() to work around signal/select race
>>     
>
> This commit breaks qemu-nbd:
>
> # ./qemu-nbd --port 1024 --persistent ../disk.qcow2 
> generates "Bus error" when I connect the client:
> # ./x86_64-softmmu/qemu-system-x86_64 -hda ../etch64.qcow2 -hdb
> nbd:localhost:1024
>
> * gdb output:
>
> Program received signal SIGBUS, Bus error.
> [Switching to Thread 0x7f3accdf76e0 (LWP 13146)]
> qemu_aio_wait () at block-raw-posix.c:541
> 541	        FD_SET(aio_sig_fd, &rdfds);
> (gdb) bt
> #0  qemu_aio_wait () at block-raw-posix.c:541
> #1  0x0000000000406245 in bdrv_read_em (bs=0x0,
> sector_num=140736764918416, 
>     buf=0x8000000000000000 <Address 0x8000000000000000 out of bounds>, 
>     nb_sectors=0) at block.c:1289
> #2  0x000000000040437a in nbd_trip (bs=0x622010, csock=8,
> size=6442450944, 
>     dev_offset=0, offset=0x7fffd4e13c78, readonly=false, 
>     data=0x7f3acccd5200 "�H\220м", data_size=1048576) at nbd.c:573
> #3  0x0000000000402d11 in main (argc=1, argv=0x1) at qemu-nbd.c:444
>   

Should be fixed now.  But the following is broken:

qemu-system-x86_64 -hda nbd:localhost:1024

That was broken before the signalfd stuff.  My guest hangs after loading 
grub.  You're command line probably suggests you knew that.  Do you know 
why this is?

Regards,

Anthony Liguori

> Laurent
>