linux/drivers/s390/block/Kconfig
David Howells 9361401eb7 [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 20:52:31 +02:00

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if S390 && BLOCK
comment "S/390 block device drivers"
depends on S390
config BLK_DEV_XPRAM
tristate "XPRAM disk support"
depends on S390
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"
depends on DASD
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".
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.
endif