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ide: remove broken disk byte-swapping support

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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>
This commit is contained in:
Bartlomiej Zolnierkiewicz
2008-01-26 20:13:09 +01:00
parent 3a5015cc9d
commit 9e47be0c97
5 changed files with 3 additions and 41 deletions
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1
drivers/ide/ide-disk.c
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@@ -761,7 +761,6 @@ static void idedisk_add_settings(ide_drive_t *drive)
ide_add_setting(drive, "bios_head", SETTING_RW, TYPE_BYTE, 0, 255, 1, 1, &drive->bios_head, NULL);
ide_add_setting(drive, "bios_sect", SETTING_RW, TYPE_BYTE, 0, 63, 1, 1, &drive->bios_sect, NULL);
ide_add_setting(drive, "address", SETTING_RW, TYPE_BYTE, 0, 2, 1, 1, &drive->addressing, set_lba_addressing);
ide_add_setting(drive, "bswap", SETTING_READ, TYPE_BYTE, 0, 1, 1, 1, &drive->bswap, NULL);
ide_add_setting(drive, "multcount", SETTING_RW, TYPE_BYTE, 0, id->max_multsect, 1, 1, &drive->mult_count, set_multcount);
ide_add_setting(drive, "nowerr", SETTING_RW, TYPE_BYTE, 0, 1, 1, 1, &drive->nowerr, set_nowerr);
ide_add_setting(drive, "lun", SETTING_RW, TYPE_INT, 0, 7, 1, 1, &drive->lun, NULL);