kernel_optimize_test/block/Kconfig
Bartlomiej Zolnierkiewicz db29a6b496 block: enable by default support for large devices and files on 32-bit archs
Enable by default support for large devices and files (CONFIG_LBD):

- With 1TB disks being a commodity hardware it is quite easy to hit 2TB
  limitation while building RAIDs etc. and many distros have been using
  CONFIG_LBD=y by default already (at least Fedora 10 and openSUSE 11.1).

- This should also prevent a subtle ext4 filesystem compatibility issue:
  mke2fs.ext4 defaults to creating filesystems with huge_files feature
  enabled and such filesystems cannot be later mounted read-write on
  machines with CONFIG_LBD=n (it should be quite easy to hit this issue
  when trying to use filesystem created using distro kernel on system
  running the self-build kernel, think about USB disk enclosures & co.).

While at it:

- Clarify config option help text w.r.t. mounting ext4 filesystems
  (they can be mounted with CONFIG_LBD=n but in the read-only mode).

Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-04-28 07:37:33 +02:00

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#
# Block layer core configuration
#
menuconfig BLOCK
bool "Enable the block layer" if EMBEDDED
default y
help
Provide block layer support for the kernel.
Disable this option to remove the block layer support from the
kernel. This may be useful for embedded devices.
If this option is disabled:
- block device files will become unusable
- some filesystems (such as ext3) will become unavailable.
Also, SCSI character devices and USB storage will be disabled since
they make use of various block layer definitions and facilities.
Say Y here unless you know you really don't want to mount disks and
suchlike.
if BLOCK
config LBD
bool "Support for large block devices and files"
depends on !64BIT
default y
help
Enable block devices or files of size 2TB and larger.
This option is required to support the full capacity of large
(2TB+) block devices, including RAID, disk, Network Block Device,
Logical Volume Manager (LVM) and loopback.
This option also enables support for single files larger than
2TB.
The ext4 filesystem requires that this feature be enabled in
order to support filesystems that have the huge_file feature
enabled. Otherwise, it will refuse to mount in the read-write
mode any filesystems that use the huge_file feature, which is
enabled by default by mke2fs.ext4.
The GFS2 filesystem also requires this feature.
If unsure, say Y.
config BLK_DEV_BSG
bool "Block layer SG support v4 (EXPERIMENTAL)"
depends on EXPERIMENTAL
---help---
Saying Y here will enable generic SG (SCSI generic) v4 support
for any block device.
Unlike SG v3 (aka block/scsi_ioctl.c drivers/scsi/sg.c), SG v4
can handle complicated SCSI commands: tagged variable length cdbs
with bidirectional data transfers and generic request/response
protocols (e.g. Task Management Functions and SMP in Serial
Attached SCSI).
If unsure, say N.
config BLK_DEV_INTEGRITY
bool "Block layer data integrity support"
---help---
Some storage devices allow extra information to be
stored/retrieved to help protect the data. The block layer
data integrity option provides hooks which can be used by
filesystems to ensure better data integrity.
Say yes here if you have a storage device that provides the
T10/SCSI Data Integrity Field or the T13/ATA External Path
Protection. If in doubt, say N.
endif # BLOCK
config BLOCK_COMPAT
bool
depends on BLOCK && COMPAT
default y
source block/Kconfig.iosched