cvs commit: src/sys/dev/usb umass.c

Poul-Henning Kamp phk at
Wed Feb 28 06:08:47 UTC 2007

In message <200702272233.l1RMXocb004983 at>, Warner Losh write

>  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.
>  Create a new quirk READ_CAPACITY_OFFBY1 

A better idea would be to have scsi_da.c try to read the 
last sector and chop it if it fails.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

More information about the cvs-src mailing list