[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 20:45:40 +02:00
|
|
|
if S390 && BLOCK
|
2005-04-17 00:20:36 +02:00
|
|
|
|
|
|
|
|
comment "S/390 block device drivers"
|
2006-01-06 09:19:28 +01:00
|
|
|
depends on S390
|
2005-04-17 00:20:36 +02:00
|
|
|
|
|
|
|
|
config BLK_DEV_XPRAM
|
|
|
|
|
tristate "XPRAM disk support"
|
2006-01-06 09:19:28 +01:00
|
|
|
depends on S390
|
2005-04-17 00:20:36 +02:00
|
|
|
help
|
|
|
|
|
Select this option if you want to use your expanded storage on S/390
|
|
|
|
|
or zSeries as a disk. This is useful as a _fast_ swap device if you
|
|
|
|
|
want to access more than 2G of memory when running in 31 bit mode.
|
|
|
|
|
This option is also available as a module which will be called
|
|
|
|
|
xpram. If unsure, say "N".
|
|
|
|
|
|
|
|
|
|
config DCSSBLK
|
|
|
|
|
tristate "DCSSBLK support"
|
|
|
|
|
help
|
|
|
|
|
Support for dcss block device
|
|
|
|
|
|
|
|
|
|
config DASD
|
|
|
|
|
tristate "Support for DASD devices"
|
|
|
|
|
depends on CCW
|
|
|
|
|
help
|
|
|
|
|
Enable this option if you want to access DASDs directly utilizing
|
|
|
|
|
S/390s channel subsystem commands. This is necessary for running
|
|
|
|
|
natively on a single image or an LPAR.
|
|
|
|
|
|
|
|
|
|
config DASD_PROFILE
|
|
|
|
|
bool "Profiling support for dasd devices"
|
|
|
|
|
depends on DASD
|
|
|
|
|
help
|
|
|
|
|
Enable this option if you want to see profiling information
|
|
|
|
|
in /proc/dasd/statistics.
|
|
|
|
|
|
|
|
|
|
config DASD_ECKD
|
|
|
|
|
tristate "Support for ECKD Disks"
|
|
|
|
|
depends on DASD
|
|
|
|
|
help
|
|
|
|
|
ECKD devices are the most commonly used devices. You should enable
|
|
|
|
|
this option unless you are very sure to have no ECKD device.
|
|
|
|
|
|
|
|
|
|
config DASD_FBA
|
|
|
|
|
tristate "Support for FBA Disks"
|
|
|
|
|
depends on DASD
|
|
|
|
|
help
|
|
|
|
|
Select this option to be able to access FBA devices. It is safe to
|
|
|
|
|
say "Y".
|
|
|
|
|
|
|
|
|
|
config DASD_DIAG
|
|
|
|
|
tristate "Support for DIAG access to Disks"
|
2006-03-24 12:15:24 +01:00
|
|
|
depends on DASD
|
2005-04-17 00:20:36 +02:00
|
|
|
help
|
|
|
|
|
Select this option if you want to use Diagnose250 command to access
|
|
|
|
|
Disks under VM. If you are not running under VM or unsure what it is,
|
|
|
|
|
say "N".
|
|
|
|
|
|
2006-03-24 12:15:25 +01:00
|
|
|
config DASD_EER
|
|
|
|
|
bool "Extended error reporting (EER)"
|
|
|
|
|
depends on DASD
|
|
|
|
|
help
|
|
|
|
|
This driver provides a character device interface to the
|
|
|
|
|
DASD extended error reporting. This is only needed if you want to
|
|
|
|
|
use applications written for the EER facility.
|
|
|
|
|
|
2005-04-17 00:20:36 +02:00
|
|
|
endif
|
