From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Tokarev <mjt@tls.msk.ru>
Subject: Re: more about serial ports: do they even work?
Date: Tue, 03 Feb 2009 00:32:40 +0300
Message-ID: <49876678.4090808@msgid.tls.msk.ru>
References: <497E1B15.2090908@msgid.tls.msk.ru> <497E1F7D.90300@msgid.tls.msk.ru> <49876547.1080904@cisco.com>
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Cc: KVM list <kvm@vger.kernel.org>, qemu-devel@nongnu.org
To: "David S. Ahern" <daahern@cisco.com>
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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);

>              if (sarg | CHR_TIOCM_DTR)
>                  targ |= TIOCM_DTR;
>              if (sarg | CHR_TIOCM_RTS)
>                  targ |= TIOCM_RTS;
>              ioctl(s->fd_in, TIOCMSET, &targ);
>          }
>          break;
>      default:
>          return -ENOTSUP;
>      }
> 
> Is this approach palatable to folks?
> 
> david

/mjt