From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57504) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gVI8z-0001yi-5L for qemu-devel@nongnu.org; Fri, 07 Dec 2018 10:34:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gVI8v-0008Gq-7Q for qemu-devel@nongnu.org; Fri, 07 Dec 2018 10:34:21 -0500 Date: Fri, 7 Dec 2018 15:34:00 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20181207153400.GM13784@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <1544108924-10841-1-git-send-email-paul.durrant@citrix.com> <1544108924-10841-4-git-send-email-paul.durrant@citrix.com> <20181207143525.GF18875@perard.uk.xensource.com> <20181207152601.GH18875@perard.uk.xensource.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181207152601.GH18875@perard.uk.xensource.com> Subject: Re: [Qemu-devel] [PATCH v2 03/18] xen: introduce 'xen-block', 'xen-disk' and 'xen-cdrom' List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony PERARD Cc: Paul Durrant , Kevin Wolf , Stefano Stabellini , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" , Max Reitz , "xen-devel@lists.xenproject.org" On Fri, Dec 07, 2018 at 03:26:01PM +0000, Anthony PERARD wrote: > On Fri, Dec 07, 2018 at 02:39:40PM +0000, Paul Durrant wrote: > > > -----Original Message----- > > > From: Anthony PERARD [mailto:anthony.perard@citrix.com] > > > Sent: 07 December 2018 14:35 > > > To: Paul Durrant > > > Cc: qemu-devel@nongnu.org; qemu-block@nongnu.org; xen- > > > devel@lists.xenproject.org; Kevin Wolf ; Max Reitz > > > ; Stefano Stabellini > > > Subject: Re: [PATCH v2 03/18] xen: introduce 'xen-block', 'xen-disk' and > > > 'xen-cdrom' > > > > > > On Thu, Dec 06, 2018 at 03:08:29PM +0000, Paul Durrant wrote: > > > > +static char *disk_to_vbd_name(unsigned int disk) > > > > +{ > > > > + char *name, *prefix = (disk >= 26) ? > > > > + disk_to_vbd_name((disk / 26) - 1) : g_strdup(""); > > > > + > > > > + name = g_strdup_printf("%s%c", prefix, 'a' + disk); > > > > > > I don't think that works, if disk is 27, we do ('a' + 27) here. It's > > > probably missing a `disk % 26`. > > > > Damn, yes I was not allowing the >2 letters. > > > > > > > > > + g_free(prefix); > > > > + > > > > + return name; > > > > +} > > > > > > [...] > > > > > > > +static unsigned int vbd_name_to_disk(const char *name, const char > > > **endp) > > > > +{ > > > > + unsigned int disk = 0; > > > > + > > > > + while (*name != '\0') { > > > > + if (!g_ascii_isalpha(*name) || !g_ascii_islower(*name)) { > > > > + break; > > > > + } > > > > + > > > > + disk *= 26; > > > > + disk += *name++ - 'a'; > > > > + } > > > > + *endp = name; > > > > + > > > > + return disk; > > > > +} > > > > + > > > > +static void xen_block_set_vdev(Object *obj, Visitor *v, const char > > > *name, > > > > + void *opaque, Error **errp) > > > > +{ > > > > > > Setting vdev doesn't work. I've tried to add a disk `xvdaa', and it > > > result in `xvda', or `d0p0' (in the trace). (Same result with `xvdaaa', > > > and 'xvdba' gives 'xvdaa'/d26p0) > > > > > > > Ok, that's weird. I'll have to figure that out. > > It's probably because 'a' is somtime 0 and sometime is 1. > > 'a' should be 0 > 'aa' should be 26, > 'aaa' Seems to be 702. > > 'xvda': 0 -> 0 * 1 > 'xvdz': 25 -> 25 * 1 > 'xvdaa': 26 -> 1 * 26 + 0 * 1 > 'xvdaaa': 702 -> 1 * 26^2 + 1 * 26 + 0 * 1 > > So, it's weird. Have fun fixing the algorithm for that. Libvirt has code for going in both directions, that's LGPLv2+ licensed if you want it: https://libvirt.org/git/?p=libvirt.git;a=blob;f=src/util/virutil.c;h=279e6aedc0f5921c850130499fc95c7d4a1e34c9;hb=HEAD#l546 Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|