From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: more about serial ports: do they even work? Date: Tue, 03 Feb 2009 11:13:46 +0300 Message-ID: <4987FCBA.7020104@msgid.tls.msk.ru> References: <497E1B15.2090908@msgid.tls.msk.ru> <497E1F7D.90300@msgid.tls.msk.ru> <49876547.1080904@cisco.com> <49876678.4090808@msgid.tls.msk.ru> <4987674E.9050201@cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: KVM list , qemu-devel@nongnu.org To: "David S. Ahern" Return-path: Received: from isrv.corpit.ru ([81.13.33.159]:51697 "EHLO isrv.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751599AbZBCIOK (ORCPT ); Tue, 3 Feb 2009 03:14:10 -0500 In-Reply-To: <4987674E.9050201@cisco.com> Sender: kvm-owner@vger.kernel.org List-ID: David S. Ahern wrote: > Michael Tokarev wrote: >> David S. Ahern wrote: >>> I don't recall seeing a followup to this post. >>> >>> To put Michael's second suggestion into patch form, the following fixes >>> the problem for me: >>> >>> --- kvm-81.orig/qemu/qemu-char.c 2008-12-14 06:16:27.000000000 -0700 >>> +++ kvm-81/qemu/qemu-char.c 2009-02-02 14:12:20.000000000 -0700 >>> @@ -1078,20 +1078,21 @@ >>> if (sarg | TIOCM_DTR) >>> *targ |= CHR_TIOCM_DTR; >>> if (sarg | TIOCM_RTS) >>> *targ |= CHR_TIOCM_RTS; >>> } >>> break; >>> case CHR_IOCTL_SERIAL_SET_TIOCM: >>> { >>> int sarg = *(int *)arg; >>> int targ = 0; >>> + ioctl(s->fd_in, TIOCMGET, &targ); >> here, one more operation is necessary: >> targ &= ~(TIOCM_DTR|TIOCM_RTS); > > Interesting. that change was not needed to fix my problem. It just means you (or, rather, your guests) never really needed to DROP those signal lines, only to raise them. >>> if (sarg | CHR_TIOCM_DTR) >>> targ |= TIOCM_DTR; >>> if (sarg | CHR_TIOCM_RTS) >>> targ |= TIOCM_RTS; Without that line above, the code never drops the two bits, once set they can't be "removed" anymore. By the way, this is upstream qemu issue, not kvm one, and has to be pushed as such. Good you CC'd qemu list. /mjt