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| author | Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> | 2008-01-26 20:13:09 +0100 |
|---|---|---|
| committer | Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> | 2008-01-26 20:13:09 +0100 |
| commit | 9e47be0c97f7357b80e91dc0632e9cce2eb025e0 (patch) | |
| tree | 7047b2b3c9ac094b801d376e4bbb95292b1962ac /Documentation | |
| parent | 3a5015cc9d7051ce8e706ef48276d8484aac0c4b (diff) | |
ide: remove broken disk byte-swapping support
Remove broken disk byte-swapping support:
- it can cause a data corruption on SMP (or if using PREEMPT on UP)
- all data coming from disk are byte-swapped by taskfile_*_data() which
results in incorrect identify data being reported by /proc/ide/ and IOCTLs
- "hdx=bswap/byteswap" kernel parameter has been broken on m68k host drivers
(including Atari/Q40 ones) since 2.5.x days (because of 'hwif' zero-ing)
- byte-swapping is limited to PIO transfers (for working with TiVo disks on
x86 machines using user-space solutions or dm-byteswap should result in
much better performance because DMA can be used)
For previous discussions please see:
http://www.ussg.iu.edu/hypermail/linux/kernel/0201.0/0768.html
http://lkml.org/lkml/2004/2/28/111
[ I have dm-byteswap device mapper target if somebody is interested
(patch is for 2.6.4 though but I'll dust it off if needed). ]
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ide.txt | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/Documentation/ide.txt b/Documentation/ide.txt index b29ccb43d6cc..94e2e3b9e77f 100644 --- a/Documentation/ide.txt +++ b/Documentation/ide.txt @@ -244,10 +244,6 @@ Summary of ide driver parameters for kernel command line "hdx=nodma" : disallow DMA - "hdx=swapdata" : when the drive is a disk, byte swap all data - - "hdx=bswap" : same as above.......... - "hdx=scsi" : the return of the ide-scsi flag, this is useful for allowing ide-floppy, ide-tape, and ide-cdrom|writers to use ide-scsi emulation on a device specific option. |