From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42194) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UnsZ7-000665-Kg for qemu-devel@nongnu.org; Sat, 15 Jun 2013 11:38:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UnsZ6-0001Pr-0n for qemu-devel@nongnu.org; Sat, 15 Jun 2013 11:38:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29437) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UnsZ5-0001Pe-Oz for qemu-devel@nongnu.org; Sat, 15 Jun 2013 11:38:55 -0400 Message-ID: <51BC8A8B.3030607@redhat.com> Date: Sat, 15 Jun 2013 16:38:51 +0100 From: Eric Blake MIME-Version: 1.0 References: <4543955.Y102znvq4W@al> <51BC84CF.5000802@redhat.com> <2801661.HtiIQHWZAa@al> In-Reply-To: <2801661.HtiIQHWZAa@al> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="----enig2ODOIPOCHAXLNQVWOSWTD" Subject: Re: [Qemu-devel] [PATCH] chardev: add baud parameter for serial host device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Wu Cc: Anthony Liguori , qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) ------enig2ODOIPOCHAXLNQVWOSWTD Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 06/15/2013 04:25 PM, Peter Wu wrote: > On Saturday 15 June 2013 16:14:23 Eric Blake wrote: >> On 06/08/2013 10:49 PM, Peter Wu wrote: >>> When QEMU starts, it always changes the serial port parameters includ= ing >>> baud rate. This confused my guest which thought it was outputting at = 9600 >>> baud while it was in fact changed to 115200. >>> >>> After this patch, I can use `-serial /dev/ttyS0,baud=3D9600` to overr= ide the >>> default baud rate of 115200. Documentation is updated as well, so tha= t >>> users know about the new `baud` parameter for `-serial` and `-chardev= >>> serial` (and its alias `-chardev tty`). >>> >>> Note that the baud option is not implemented for Windows. QEMU does n= ot >>> change the default baud rate on Windows anyway. If somebody is going = to >>> implement it, do not forget to update the documentation on "COM" devi= ces >>> which is also of backend serial. >>> >>> - 'serial' : 'ChardevHostdev', >>> + 'serial' : 'ChardevSerial', >> >> without introspection, libvirt has no idea whether 'baud' is supported= >> in the qemu it is talking to, other than trying and failing when talki= ng >> to older qemu. This patch forms yet another reason why libvirt wants = to >> learn when we add optional parameters to a pre-existing QMP command. >=20 > I have do not use libvirt, do you want me to do further things for this= patch=20 > to get accepted? Or is it more a side-note? I'm wondering if there is an alternative that we can come up with that doesn't require the addition of an optional parameter, and therefore something that libvirt could reliably use without needing Amos' introspection support to go in first. Besides, weren't some of the other review comments in this thread questioning whether we should even allow users to set baud rate at creation, or should we be fixing the real underlying bug of not matching bare-metal hardware that always initializes to a fixed rate of 9600? That is, I think there are still unanswered questions that must be resolved before we can even decide whether an amended version of this patch is even worth including. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org ------enig2ODOIPOCHAXLNQVWOSWTD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJRvIqLAAoJEKeha0olJ0NqkH0H+gM8ZrqArU8twQSNf2xSXQ8/ UY8zJADwsVuhMUd4cUceqTC7cD1g6H4cBLYqLaU2FYV3LNfUDDrbHjSSqxJ9tg7c W72jgskdoj4NM/2ex56bqyOJ8h8RzI0SshL52GbKrFSDX5g4mFzJVfjbSvAcsErP pi85WlJNNWoZqF+8VFNz7gr/m3a9HI7PqZvmwi6BdEQ2L9vm55eVME8MxpLKFMV2 S4U88P0vVHl1qejDmDaCssopWquFNJqE6Sv5a5G/jqsQ0PXJtzTXhjh9V4cDv2S5 7nzLzj2b//Ual49OMplGY0H9+nBDxsNxQ1a0/rB84rpuWjvxN2tPaPP+w9Wr5R8= =sNed -----END PGP SIGNATURE----- ------enig2ODOIPOCHAXLNQVWOSWTD--