e815d36548
Add the sd_read_cpr() function to the sd scsi disk driver to discover if a device has multiple concurrent positioning ranges (i.e. multiple actuators on an HDD). The existence of VPD page B9h indicates if a device has multiple concurrent positioning ranges. The page content describes each range supported by the device. sd_read_cpr() is called from sd_revalidate_disk() and uses the block layer functions disk_alloc_independent_access_ranges() and disk_set_independent_access_ranges() to represent the set of actuators of the device as independent access ranges. The format of the Concurrent Positioning Ranges VPD page B9h is defined in section 6.6.6 of SBC-5. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/20211027022223.183838-3-damien.lemoal@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.