From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Marshall Subject: Re: more about serial ports: do they even work? Date: Tue, 03 Feb 2009 08:41:14 +0000 Message-ID: <4988032A.5010905@ntlworld.com> 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> <4987FCBA.7020104@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org To: kvm@vger.kernel.org Return-path: Received: from main.gmane.org ([80.91.229.2]:42766 "EHLO ciao.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751302AbZBCIzF (ORCPT ); Tue, 3 Feb 2009 03:55:05 -0500 Received: from root by ciao.gmane.org with local (Exim 4.43) id 1LUH3e-0006Zy-Gy for kvm@vger.kernel.org; Tue, 03 Feb 2009 08:55:02 +0000 Received: from cpc2-cmbg11-0-0-cust546.cmbg.cable.ntl.com ([86.22.78.35]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 03 Feb 2009 08:55:02 +0000 Received: from mark.marshall60 by cpc2-cmbg11-0-0-cust546.cmbg.cable.ntl.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 03 Feb 2009 08:55:02 +0000 In-Reply-To: <4987FCBA.7020104@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: Michael Tokarev wrote: > 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; Is this code really correct. If it is is there a comment somewhere describing why it's correct? I would have expected the lines above to be: if (sarg & CHR_TIOCM_DTR) targ |= TIOCM_DTR; if (sarg & CHR_TIOCM_RTS) targ |= TIOCM_RTS; (Just an observation as this went past). MM > > 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 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >