From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Jackson <Ian.Jackson@eu.citrix.com>
Subject: Re: [PATCH 1/1] libxl: use qemu-xen with PV guests by
	default
Date: Fri, 20 Apr 2012 14:01:03 +0100
Message-ID: <20369.24079.242104.252793@mariner.uk.xensource.com>
References: <1334926480-21094-1-git-send-email-stefano.stabellini@eu.citrix.com>
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, Ian Campbell <Ian.Campbell@citrix.com>
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Stefano Stabellini writes ("[PATCH 1/1] libxl: use qemu-xen with PV guests by default"):
> qemu-xen offers better disk performances than qemu-xen-traditional
> because it supports Linux native AIO: use it for PV guests if it is
> available.
...
> +            rc = stat(dm, &buf);
> +            /* qemu-xen unavailable, use qemu-xen-traditional */

Firstly, why not use access(2) rather than stat(2) ?

Secondly you ignore the errno value.  errnos other than ENOENT (or
perhaps ENOTDIR) should perhaps cause us to bomb out, and in any case
the errno value should be logged.

Ian.