Date: Wed, 28 Feb 2007 09:58:12 +0100 From: des@des.no (Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?=) To: Warner Losh <imp@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/usb umass.c Message-ID: <86d53ufyl7.fsf@dwp.des.no> In-Reply-To: <200702272233.l1RMXocb004983@repoman.freebsd.org> (Warner Losh's message of "Tue, 27 Feb 2007 22:33:50 %2B0000 (UTC)") References: <200702272233.l1RMXocb004983@repoman.freebsd.org>
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Warner Losh <imp@FreeBSD.org> writes: > Log: > Some USB mass storage devices return the number of sectors in response > to a READ_CAPACITY request rather than the maximum sector (off by one > problem). This causes a huge cascade of errors as the geom tasting > code tries to read the last sector (which isn't really there in the > face of this error). automated tools that manipulate disk labels and > such also have issues. >=20=20=20 > Create a new quirk READ_CAPACITY_OFFBY1 and add a quirk for the > SanDISK ImageMate that I have that suffers from this problem (the > SDDR-31). It intercepts the READ_CAPACITY response and adjusts it > from number of sectors to max sector for devices with this quirk. >=20=20=20 > Reading the Linux source suggests that there are a host of > other devices with this issue, including iPods and some popular > cameras. I've not added quirks for them, since I don't have the > devices in front of me to test. How about the following dirty hack: if the appropriate kernel option / device hint / sysctl knob is frobbed, when a READ_CAPACITY request completes, try to read the last sector, and if that doesn't work, adjust the result and print a warning to the console? DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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