Date: Mon, 12 Jul 1999 20:23:26 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: Matthew Dillon <dillon@apollo.backplane.com>, Luoqi Chen <luoqi@watermarkgroup.com>, dfr@nlsystems.com, jeremyp@gsmx07.alcatel.com.au, freebsd-current@FreeBSD.ORG, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") Message-ID: <20501.931803806@critter.freebsd.dk> In-Reply-To: Your message of "Mon, 12 Jul 1999 10:38:45 PDT." <19990712103845.39296@hydrogen.fircrest.net>
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In message <19990712103845.39296@hydrogen.fircrest.net>, John-Mark Gurney writes: >Matthew Dillon scribbled this message on Jul 12: >> p.s. I'm pretty sure that the lock prefix costs nothing on a UP system, >> and probably wouldn't be noticed on an SMP system either because the >> write-allocation overhead is already pretty bad. But I haven't tested >> it. > >actually, I'm not so sure, it guarantees that NO other bus operation >will succeed while this is happening... what happens if a pci bus >mastering card makes a modification to this value? sure, it normally >won't happen, but it can... and w/o the lock prefix, this CAN happen >from what I understand of the architecture... it locks EVERYTHING. -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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