GNU bug report logs - #12626
Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?

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Package: coreutils;

Reported by: Linda Walsh <coreutils <at> tlinx.org>

Date: Fri, 12 Oct 2012 03:13:02 UTC

Severity: normal

Done: Pádraig Brady <P <at> draigBrady.com>

Bug is archived. No further changes may be made.

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From: Eric Blake <eblake <at> redhat.com>
To: Linda Walsh <coreutils <at> tlinx.org>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, Pádraig Brady <P <at> draigBrady.com>, 12626-done <at> debbugs.gnu.org
Subject: bug#12626: Bug?: dd limited to <2G read size (2G-8K) on 64 bit machine?
Date: Fri, 12 Oct 2012 09:35:20 -0600

[Message part 1 (text/plain, inline)]
On 10/12/2012 09:25 AM, Linda Walsh wrote:

[please don't top-post on technical lists]

> 
> Hey guys, this is still a bug though:
> 
> Ishtar:dev/shm# dd if=4G of=4Ga bs=4G count=1
> 0+1 records in
> 0+1 records out
> 2147479552 bytes (2.1 GB) copied, 4.0274 s, 533 MB/s
> (note no error message....)

Nope, that's not a bug, but behavior required by POSIX.  You asked dd to
read _up to 4G_ for a count of exactly 1.  Just because the read was
short does not make it an error.

-- 
Eric Blake   eblake <at> redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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