From owner-freebsd-bugs Fri Apr 27 22: 0: 7 2001 Delivered-To: freebsd-bugs@hub.freebsd.org Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id 25CDD37B422 for ; Fri, 27 Apr 2001 22:00:04 -0700 (PDT) (envelope-from gnats@FreeBSD.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.11.1/8.11.1) id f3S504f85365; Fri, 27 Apr 2001 22:00:04 -0700 (PDT) (envelope-from gnats) Date: Fri, 27 Apr 2001 22:00:04 -0700 (PDT) Message-Id: <200104280500.f3S504f85365@freefall.freebsd.org> To: freebsd-bugs@FreeBSD.org Cc: From: Rich Wales Subject: Re: i386/26261: silo overflow problem in sio driver Reply-To: Rich Wales Sender: owner-freebsd-bugs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org The following reply was made to PR i386/26261; it has been noted by GNATS. From: Rich Wales To: freebsd-gnats-submit@freebsd.org Cc: Subject: Re: i386/26261: silo overflow problem in sio driver Date: Fri, 27 Apr 2001 21:53:32 -0700 (PDT) Earlier, I wrote: > This presumably leaves open the question of whether the problem > is due to a bug in XFree86-4.x itself, or if XFree86-4.x is > innocently tickling some FreeBSD kernel bug. The people on the "xpert@xfree86.org" list suggest that the XFree86-4 accelerator code is being overly aggressive about pipelining commands to the video card -- and, in the process, is locking up the PCI bus and interfering with the timely servicing of serial I/O interrupts. I was able to sidestep the problem (and get rid of the silo overflows) by enabling the "XaaNoScanlineCPUToScreenColorExpandFill" video driver option (this disables "indirect" CPU-to-screen color expansion). Alternatively, the "XaaNoSolidFillRect" option (disabling solid filled rectangle acceleration) also fixed the problem. In either case, I see no degradation of overall video performance. The XFree86 people are still unclear as to how video acceleration ops could lock up the PCI bus, so I suppose there might still be a bug somewhere in FreeBSD that is allowing this problem to occur. So it might not quite be time to close this PR yet. Rich Wales richw@webcom.com http://www.webcom.com/richw/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message