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https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git
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[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 <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
David Howells
Jens Axboe
parent
d366e40a1c
commit
9361401eb7
44 changed files with 308 additions and 63 deletions
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@ -2,6 +2,8 @@
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# Block device driver configuration
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#
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if BLOCK
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menu "Block devices"
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config BLK_DEV_FD
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@ -468,3 +470,5 @@ config ATA_OVER_ETH
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devices like the Coraid EtherDrive (R) Storage Blade.
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endmenu
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endif
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@ -3,7 +3,7 @@
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#
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menu "Old CD-ROM drivers (not SCSI, not IDE)"
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depends on ISA
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depends on ISA && BLOCK
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config CD_NO_IDESCSI
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bool "Support non-SCSI/IDE/ATAPI CDROM drives"
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@ -1006,6 +1006,7 @@ config GPIO_VR41XX
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config RAW_DRIVER
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tristate "RAW driver (/dev/raw/rawN) (OBSOLETE)"
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depends on BLOCK
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help
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The raw driver permits block devices to be bound to /dev/raw/rawN.
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Once bound, I/O against /dev/raw/rawN uses efficient zero-copy I/O.
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@ -655,6 +655,7 @@ void add_interrupt_randomness(int irq)
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add_timer_randomness(irq_timer_state[irq], 0x100 + irq);
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}
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#ifdef CONFIG_BLOCK
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void add_disk_randomness(struct gendisk *disk)
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{
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if (!disk || !disk->random)
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@ -667,6 +668,7 @@ void add_disk_randomness(struct gendisk *disk)
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}
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EXPORT_SYMBOL(add_disk_randomness);
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#endif
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#define EXTRACT_SIZE 10
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@ -918,6 +920,7 @@ void rand_initialize_irq(int irq)
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}
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}
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#ifdef CONFIG_BLOCK
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void rand_initialize_disk(struct gendisk *disk)
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{
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struct timer_rand_state *state;
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@ -932,6 +935,7 @@ void rand_initialize_disk(struct gendisk *disk)
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disk->random = state;
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}
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}
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#endif
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static ssize_t
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random_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
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@ -4,6 +4,8 @@
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# Andre Hedrick <[email protected]>
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#
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if BLOCK
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menu "ATA/ATAPI/MFM/RLL support"
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config IDE
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@ -1082,3 +1084,5 @@ config BLK_DEV_HD
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endif
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endmenu
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endif
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@ -2,6 +2,8 @@
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# Block device driver configuration
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#
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if BLOCK
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menu "Multi-device support (RAID and LVM)"
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config MD
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@ -251,3 +253,4 @@ config DM_MULTIPATH_EMC
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endmenu
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endif
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@ -88,7 +88,7 @@ config I2O_BUS
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config I2O_BLOCK
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tristate "I2O Block OSM"
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depends on I2O
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depends on I2O && BLOCK
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---help---
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Include support for the I2O Block OSM. The Block OSM presents disk
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and other structured block devices to the operating system. If you
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@ -21,7 +21,7 @@ config MMC_DEBUG
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config MMC_BLOCK
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tristate "MMC block device driver"
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depends on MMC
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depends on MMC && BLOCK
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default y
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help
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Say Y here to enable the MMC block device driver support.
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@ -24,7 +24,8 @@ obj-$(CONFIG_MMC_AU1X) += au1xmmc.o
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obj-$(CONFIG_MMC_OMAP) += omap.o
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obj-$(CONFIG_MMC_AT91RM9200) += at91_mci.o
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mmc_core-y := mmc.o mmc_queue.o mmc_sysfs.o
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mmc_core-y := mmc.o mmc_sysfs.o
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mmc_core-$(CONFIG_BLOCK) += mmc_queue.o
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ifeq ($(CONFIG_MMC_DEBUG),y)
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EXTRA_CFLAGS += -DDEBUG
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@ -166,7 +166,7 @@ config MTD_CHAR
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config MTD_BLOCK
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tristate "Caching block device access to MTD devices"
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depends on MTD
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depends on MTD && BLOCK
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---help---
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Although most flash chips have an erase size too large to be useful
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as block devices, it is possible to use MTD devices which are based
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@ -188,7 +188,7 @@ config MTD_BLOCK
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config MTD_BLOCK_RO
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tristate "Readonly block device access to MTD devices"
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depends on MTD_BLOCK!=y && MTD
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depends on MTD_BLOCK!=y && MTD && BLOCK
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help
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This allows you to mount read-only file systems (such as cramfs)
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from an MTD device, without the overhead (and danger) of the caching
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@ -199,7 +199,7 @@ config MTD_BLOCK_RO
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config FTL
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tristate "FTL (Flash Translation Layer) support"
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depends on MTD
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depends on MTD && BLOCK
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---help---
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This provides support for the original Flash Translation Layer which
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is part of the PCMCIA specification. It uses a kind of pseudo-
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@ -215,7 +215,7 @@ config FTL
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config NFTL
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tristate "NFTL (NAND Flash Translation Layer) support"
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depends on MTD
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depends on MTD && BLOCK
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---help---
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This provides support for the NAND Flash Translation Layer which is
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used on M-Systems' DiskOnChip devices. It uses a kind of pseudo-
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@ -238,7 +238,7 @@ config NFTL_RW
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config INFTL
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tristate "INFTL (Inverse NAND Flash Translation Layer) support"
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depends on MTD
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depends on MTD && BLOCK
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---help---
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This provides support for the Inverse NAND Flash Translation
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Layer which is used on M-Systems' newer DiskOnChip devices. It
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@ -255,7 +255,7 @@ config INFTL
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config RFD_FTL
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tristate "Resident Flash Disk (Flash Translation Layer) support"
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depends on MTD
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depends on MTD && BLOCK
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---help---
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This provides support for the flash translation layer known
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as the Resident Flash Disk (RFD), as used by the Embedded BIOS
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@ -136,7 +136,7 @@ config MTDRAM_ABS_POS
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config MTD_BLOCK2MTD
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tristate "MTD using block device"
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depends on MTD
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depends on MTD && BLOCK
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help
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This driver allows a block device to appear as an MTD. It would
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generally be used in the following cases:
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@ -1,4 +1,4 @@
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if S390
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if S390 && BLOCK
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comment "S/390 block device drivers"
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depends on S390
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@ -3,11 +3,13 @@ menu "SCSI device support"
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config RAID_ATTRS
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tristate "RAID Transport Class"
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default n
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depends on BLOCK
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---help---
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Provides RAID
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config SCSI
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tristate "SCSI device support"
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depends on BLOCK
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---help---
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If you want to use a SCSI hard disk, SCSI tape drive, SCSI CD-ROM or
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any other SCSI device under Linux, say Y and make sure that you know
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