Date: Wed, 30 Oct 2002 12:24:23 -0800 From: Luigi Rizzo <rizzo@icir.org> To: Ian Dowse <iedowse@FreeBSD.org> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/fxp if_fxp.c Message-ID: <20021030122423.B24962@carp.icir.org> In-Reply-To: <200210301908.g9UJ8uK1077790@repoman.freebsd.org>; from iedowse@FreeBSD.org on Wed, Oct 30, 2002 at 11:08:56AM -0800 References: <200210301908.g9UJ8uK1077790@repoman.freebsd.org>
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actually, before people get alarmed by this commit message, i want to make a clarification. The status field is updated only on descriptors marked as 'completed' by the card, so they are not be in use by the hardware while the driver touches it. While this commit may fix the crash that Pawel was seeing, i seriously doubt that it addresses the real problem, assuming there is a problem in the driver and not in the hardware (Pawel was mentioning that out of two identical boxes, one is panicing and the other is not, which is a bit suspect...) cheers luigi On Wed, Oct 30, 2002 at 11:08:56AM -0800, Ian Dowse wrote: > iedowse 2002/10/30 11:08:56 PST > > Modified files: > sys/dev/fxp if_fxp.c > Log: > Revision 1.136 introduced two features that may cause undefined > behaviour of the hardware: a possibly reserved bit of the receive > descriptor (RFA) `status' field is borrowed to record no-resource > (RNR) events, and the same status field is read and written to at > a time that may clash with the hardware updating this field. > > There is no hardware documentation available to determine if these > things are safe to do; the second issue almost certainly isn't, and > the first is only safe if there is documentation saying that this > bit is free to be used by the driver. The PR referenced below > provides extremely convincing evidence that the changes cause random > crashes on some (unusual) hardware. > > Since these features are only required by the DEVICE_POLLING case, > this commit makes their use conditional on that option. It does not > change the DEVICE_POLLING case, but at least people with the rare > hardware on which this code causes problems can now avoid the crashes > by not enabling DEVICE_POLLING. > > PR: kern/42260 > Reviewed by: luigi > Problem revision found by: Pawel Malachowski <pawmal@unia.3lo.lublin.pl> > Tested by: Pawel Malachowski <pawmal@unia.3lo.lublin.pl> > MFC after: 1 week > > Revision Changes Path > 1.142 +14 -1 src/sys/dev/fxp/if_fxp.c To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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