From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: raw disks no longer work in latest kvm (kvm-88 was fine)
Date: Sun, 07 Mar 2010 21:10:16 +0200
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References: <4B92BF97.4040001@nagafix.co.uk> <4B92C90B.4030807@msgid.tls.msk.ru> <4B932829.8090503@nagafix.co.uk> <4B9372B6.3050408@msgid.tls.msk.ru> <20100307100022.GA23201@infradead.org> <4B93A624.8010707@nagafix.co.uk> <4B93AF8A.3070805@nagafix.co.uk> <4B93C2F9.7030904@msgid.tls.msk.ru> <4B93DE3F.4090103@nagafix.co.uk> <4B93DFF0.5050905@redhat.com> <20100307172151.GA24859@infradead.org> <4B93E29E.6090609@redhat.com> <4B93E9EE.6020701@nagafix.co.uk> <4B93F4A4.9050003@redhat.com> <4B93F96E.30508@nagafix.co.uk>
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Cc: Christoph Hellwig <hch@infradead.org>, kvm@vger.kernel.org
To: Antoine Martin <antoine@nagafix.co.uk>
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On 03/07/2010 09:07 PM, Antoine Martin wrote:
>>>> Antoine, can you check this?  ltrace may help,
>>> This the only part that looked slightly relevant:
>>> [pid 26883] __xstat64(1, "./vm/media_fs", 0x7fff92e40500) = 0
>>> [pid 26883] malloc(48)                           = 0x2a38d60
>>> [pid 26883] memset(0x2a38d60, '\000', 48)        = 0x2a38d60
>>> [pid 26883] open64("./vm/media_fs", 540674, 00)  = 12
>>> [pid 26883] posix_memalign(0x7fff92e40560, 512, 16384, -1, 48) = 0
>>> [pid 26883] lseek64(12, 0, 2, 0x7f404f2f3e60, 4) = 0x133c4820600
>>
>>
>> Where's pread/preadv?  Did you use -f?
>
> Yes I did.
> ltrace -f bash ./vm/start.sh >& trace.log

Well, some variant of pread should have shown up.  Maybe it's the ltrace 
-f race.

>>>> or run 'strings libc.so | grep pread'.
>>>>
>>> strings /lib/libc.so.6 | grep pread
>>> preadv
>>> preadv64
>>> pread
>>> __pread64_chk
>>> __pread64
>>> __pread_chk
>>>
>>
>> So it does seem glibc emulates preadv.
>>
>> Perhaps https://bugzilla.redhat.com/show_bug.cgi?id=563103 ?
> This a gentoo box... but yes, this does look similar doesn't it?

What version of glibc do you have installed?

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.