diff options
author | David Howells <dhowells@redhat.com> | 2006-09-30 22:45:40 +0400 |
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committer | Jens Axboe <axboe@nelson.home.kernel.dk> | 2006-09-30 22:52:31 +0400 |
commit | 9361401eb7619c033e2394e4f9f6d410d6719ac7 (patch) | |
tree | 04b94a71f2366988c17740d1c16cfbdec41d5d2e /drivers/char/random.c | |
parent | d366e40a1cabd453be6e2609caa7e12f9ca17b1f (diff) | |
download | linux-9361401eb7619c033e2394e4f9f6d410d6719ac7.tar.xz |
[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>
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r-- | drivers/char/random.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c index 4c3a5ca9d8f7..b430a12eb819 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -655,6 +655,7 @@ void add_interrupt_randomness(int irq) add_timer_randomness(irq_timer_state[irq], 0x100 + irq); } +#ifdef CONFIG_BLOCK void add_disk_randomness(struct gendisk *disk) { if (!disk || !disk->random) @@ -667,6 +668,7 @@ void add_disk_randomness(struct gendisk *disk) } EXPORT_SYMBOL(add_disk_randomness); +#endif #define EXTRACT_SIZE 10 @@ -918,6 +920,7 @@ void rand_initialize_irq(int irq) } } +#ifdef CONFIG_BLOCK void rand_initialize_disk(struct gendisk *disk) { struct timer_rand_state *state; @@ -932,6 +935,7 @@ void rand_initialize_disk(struct gendisk *disk) disk->random = state; } } +#endif static ssize_t random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos) |