Date: Thu, 02 Feb 2006 15:06:42 -0700 From: Scott Long <scottl@samsco.org> To: Matthew Jacob <mj@feral.com> Cc: freebsd-scsi@freebsd.org, Florent Thoumie <flz@xbsd.org>, "Kenneth D. Merry" <ken@freebsd.org>, Nate Lawson <nate@root.org> Subject: Re: cvs commit: src/sys/cam/scsi scsi_da.c src/sys/dev/usb umass.c usbdevs Message-ID: <43E28272.30704@samsco.org> In-Reply-To: <20060202135123.K99168@ns1.feral.com> References: <20060130202806.DCC7916A4CA@hub.freebsd.org> <43DEF43A.6090804@root.org> <20060130213338.H79194@ns1.feral.com> <200601311239.10248.flz@xbsd.org> <43E06B06.80405@root.org> <20060202175041.GA92109@nargothrond.kdm.org> <20060202095828.D97756@ns1.feral.com> <43E252EC.1050803@root.org> <43E25C4D.9020804@samsco.org> <43E2650D.1060109@root.org> <20060202130620.A99168@ns1.feral.com> <43E27E58.4020606@samsco.org> <20060202135123.K99168@ns1.feral.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Matthew Jacob wrote: >>> >>> >>> And how will you distinguish between "not currently enabled" and "not >>> supported"? >>> >> >> If WCE is not supported, will the device lie and report the WCE bit as >> set? >> > > No. But a device could have it turned off and you wouldn't then infer > that you *could*. I guess I don't follow. There was a suggestion to read page 8 during the da device probe, cache the WCE value, and act on it accordingly later on. There was also a suggestion to read the page on demand as part of the immediate decision to do the SYNC CACHE. As much of a hassle as it could be, the latter is likely the better approach as it eliminates the messy state tracking that you'd have to do on the user. Who wants to hack up the pass driver to trap mode page writes and then try to correlate which da device to pass that info on to? And yeah, if the device is able to change the state on its own, there is no way the first approach can work. Scott
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?43E28272.30704>