From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: raw disks no longer work in latest kvm (kvm-88 was fine)
Date: Sun, 7 Mar 2010 12:21:51 -0500
Message-ID: <20100307172151.GA24859@infradead.org>
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>
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Cc: Antoine Martin <antoine@nagafix.co.uk>,
	Michael Tokarev <mjt@tls.msk.ru>, kvm@vger.kernel.org
To: Avi Kivity <avi@redhat.com>
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On Sun, Mar 07, 2010 at 07:18:40PM +0200, Avi Kivity wrote:
>> The only things that stands out is this before the "read failed" message:
>> [pid  9098] lseek(12, 0, SEEK_END)      = 1321851815424
>> [pid  9121] pread(12, 0x7fa50a0e47d0, 2048, 0) = -1 EINVAL (Invalid  
>> argument)
>>
>
> The buffer is unaligned here, yet the file was opened with O_DIRECT  
> (cache=none).  This is strange, since alignment is not related to disk 
> size.

The other interesting thing is that it's using pread - which means
it's a too old kernel to use preadv and thus a not very well tested
codepath with current qemu.