LinuxPCCardSupport < DULG

%SECTION0{name=LinuxPccardSupport}% PC Card Support in Linux

The standard way to use PC Cards in a Linux system is to install the
"PCMCIA Card Services" package. This is a quite complex set of kernel
modules and tools that take care of things like automatic detection
and handling of "card insert" or "remove" events, identification of
the inserted cards, loading the necessary device drivers, etc. This is
a very powerful package, but for embedded applications it has several
serious disadvantages:

   * Memory footprint - the package consists of a lot of tools and
     modules that take a lot of space both in the root filesystem and
     in system RAM when running

   * Chicken and Egg Problem - the package loads the needed device
     drivers as kernel modules, so it needs a root filesystem on
     another device; that means that you cannot easily put the root
     filesystem on a PC Card.

For "disk" type PC Cards (FlashDisks, CompactFlash, Hard Disk Adapters
- basicly anything that looks like an ordinary IDE drive) an
alternative solution is available: direct support within the Linux
kernel. This has the big advantage of minimal memory footprint, but of
course it comes with a couple of disadvantages, too:

   * It works only with "disk" type PC Cards - no support for modems,
     network cards, etc; for these you still need the PCMCIA Card
     Services package.

   * There is no support for "hot plug", i. e. you cannot insert or
     remove the card while Linux is running. (Well, of course you
     =can= do this, but either you willnot be able to access any card
     inserted, or when you remove a card you will most likely crash
     the system. Don't do it - you have been warned!)

   * The code relies on initialization of the PCMCIA controller by the
     firmware (of course U-Boot will do exactly what's required).

On the other hand these are no real restrictions for use in an
Embedded System.

To enable the "direct IDE support" you have to select the following
Linux kernel configuration options:

<verbatim>
CONFIG_IDE=y
CONFIG_BLK_DEV_IDE=y
CONFIG_BLK_DEV_IDEDISK=y
CONFIG_IDEDISK_MULTI_MODE=y
CONFIG_BLK_DEV_MPC8xx_IDE=y
CONFIG_BLK_DEV_IDE_MODES=y
</verbatim>

and, depending on which partition types and languages you want to
support:

<verbatim>
CONFIG_PARTITION_ADVANCED=y
CONFIG_MAC_PARTITION=y
CONFIG_MSDOS_PARTITION=y
CONFIG_NLS=y
CONFIG_NLS_DEFAULT="y"
CONFIG_NLS_ISO8859_1=y
CONFIG_NLS_ISO8859_15=y
</verbatim>

With these options you will see messages like the following when you
boot the Linux kernel:

<verbatim>
...
Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
PCMCIA slot B: phys mem e0000000...ec000000 (size 0c000000)
Card ID:   CF 128MB CH
 Fixed Disk Card
 IDE interface
 [silicon] [unique] [single] [sleep] [standby] [idle] [low power]
hda: probing with STATUS(0x50) instead of ALTSTATUS(0x41)
hda: CF 128MB, ATA DISK drive
ide0 at 0xc7000320-0xc7000327,0xc3000106 on irq 13
hda: 250368 sectors (128 MB) w/16KiB Cache, CHS=978/8/32
Partition check:
 hda: hda1 hda2 hda3 hda4
...
</verbatim>

You can now access your PC Card "disk" like any normal IDE drive. If
you start with a new drive, you have to start by creating a new
partition table. For [[PowerPC][Power Architecture]]® systems, there are two commonly used
options:

%SECTION1{name=PartitionMacOS}%   Using a <nop>MacOS Partition Table

A !MacOS partition table is the "native" partition table format on
[[PowerPC][Power Architecture]]® systems; most desktop [[PowerPC][Power Architecture]]® systems use it, so you may
prefer it when you have [[PowerPC][Power Architecture]]® development systems around.

To format your "disk" drive with a !MacOS partition table you can use
the =pdisk= command:

We start printing the help menu, re-initializing the partition table
and then printing the new, empty partition table so that we know the
block numbers when we want to create new partitions:

<verbatim>
# pdisk /dev/hda
Edit /dev/hda -
Command (? for help): ?
Notes:
  Base and length fields are blocks, which vary in size between media.
  The base field can be &lt;nth&gt;p; i.e. use the base of the nth partition.
  The length field can be a length followed by k, m, g or t to indicate
  kilo, mega, giga, or tera bytes; also the length can be &lt;nth&gt;p; i.e. use
  the length of the nth partition.
  The name of a partition is descriptive text.

Commands are:
  h    help
  p    print the partition table
  P    (print ordered by base address)
  i    initialize partition map
  s    change size of partition map
  c    create new partition (standard MkLinux type)
  C    (create with type also specified)
  n    (re)name a partition
  d    delete a partition
  r    reorder partition entry in map
  w    write the partition table
  q    quit editing (don't save changes)
Command (? for help): i
map already exists
do you want to reinit? [n/y]: y
Command (? for help): p

Partition map (with 512 byte blocks) on '/dev/hda'
 #:                type name    length   base    ( size )
 1: Apple_partition_map Apple       63 @ 1
 2:          Apple_Free Extra  1587536 @ 64      (775.2M)

Device block size=512, Number of Blocks=1587600 (775.2M)
DeviceType=0x0, DeviceId=0x0
</verbatim>

At first we create two small partitions that will be used to store a
Linux boot image; a compressed Linux kernel is typically around 400
... 500 kB, so chosing a partition size of 2 MB is more than generous.
2 MB coresponds to 4096 disk blocks of 512 bytes each, so we enter:

<verbatim>
Command (? for help): C
First block: 64
Length in blocks: 4096
Name of partition: boot0
Type of partition: PPCBoot
Command (? for help): p

Partition map (with 512 byte blocks) on '/dev/hda'
 #:                type name    length   base    ( size )
 1: Apple_partition_map Apple       63 @ 1
 2:             PPCBoot boot0     4096 @ 64      (  2.0M)
 3:          Apple_Free Extra  1583440 @ 4160    (773.2M)

Device block size=512, Number of Blocks=1587600 (775.2M)
DeviceType=0x0, DeviceId=0x0
</verbatim>

To be able to select between two kernel images (for instance when we
want to do a field upgrade of the Linux kernel) we create a second
boot partition of exactly the same size:

<verbatim>
Command (? for help): C
First block: 4160
Length in blocks: 4096
Name of partition: boot1
Type of partition: PPCBoot
Command (? for help): p

Partition map (with 512 byte blocks) on '/dev/hda'
 #:                type name    length   base    ( size )
 1: Apple_partition_map Apple       63 @ 1
 2:             PPCBoot boot0     4096 @ 64      (  2.0M)
 3:             PPCBoot boot1     4096 @ 4160    (  2.0M)
 4:          Apple_Free Extra  1579344 @ 8256    (771.2M)

Device block size=512, Number of Blocks=1587600 (775.2M)
DeviceType=0x0, DeviceId=0x0
</verbatim>

Now we create a swap partition - 64 MB should be more than sufficient
for our Embedded System; 64 MB means 64*1024*2 = 131072 disk blocks
of 512 bytes:

<verbatim>
Command (? for help): C
First block: 8256
Length in blocks: 131072
Name of partition: swap
Type of partition: swap
Command (? for help): p

Partition map (with 512 byte blocks) on '/dev/hda'
 #:                type name    length   base    ( size )
 1: Apple_partition_map Apple       63 @ 1
 2:             PPCBoot boot0     4096 @ 64      (  2.0M)
 3:             PPCBoot boot1     4096 @ 4160    (  2.0M)
 4:                swap swap    131072 @ 8256    ( 64.0M)
 5:          Apple_Free Extra  1448272 @ 139328  (707.2M)

Device block size=512, Number of Blocks=1587600 (775.2M)
DeviceType=0x0, DeviceId=0x0
</verbatim>

Finally, we dedicate all the remaining space to the root partition:

<verbatim>
Command (? for help): C
First block: 139328
Length in blocks: 1448272
Name of partition: root
Type of partition: Linux
Command (? for help): p

Partition map (with 512 byte blocks) on '/dev/hda'
 #:                type name    length   base    ( size )
 1: Apple_partition_map Apple       63 @ 1
 2:             PPCBoot boot0     4096 @ 64      (  2.0M)
 3:             PPCBoot boot1     4096 @ 4160    (  2.0M)
 4:                swap swap    131072 @ 8256    ( 64.0M)
 5:               Linux root   1448272 @ 139328  (707.2M)

Device block size=512, Number of Blocks=1587600 (775.2M)
DeviceType=0x0, DeviceId=0x0
</verbatim>

To make our changes permanent we must write the new partition table
to the disk, before we quit the =pdisk= program:

<verbatim>
Command (? for help): w
Writing the map destroys what was there before. Is that okay? [n/y]: y
 hda: [mac] hda1 hda2 hda3 hda4 hda5
 hda: [mac] hda1 hda2 hda3 hda4 hda5
Command (? for help): q
</verbatim>

Now we can initialize the swap space and the filesystem:

<verbatim>
# mkswap /dev/hda4
Setting up swapspace version 1, size = 67104768 bytes
# mke2fs /dev/hda5
mke2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
90624 inodes, 181034 blocks
9051 blocks (5.00%) reserved for the super user
First data block=0
6 block groups
32768 blocks per group, 32768 fragments per group
15104 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840

Writing inode tables: done
Writing superblocks and filesystem accounting information: done
</verbatim>

%SECTION1{name=PartitionDOS}% Using a MS-DOS Partition Table

The MS-DOS partition table is especially common on PC type computers,
which these days means nearly everywhere. You will prefer this format
if you want to exchange your "disk" media with any PC type host
system.

The =fdisk= command is used to create MS-DOS type
partition tables; to create the same partitioning scheme as above you
would use the following commands:

<verbatim>
# fdisk /dev/hda
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.


The number of cylinders for this disk is set to 1575.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)
</verbatim>


<verbatim>
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1575, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1575, default 1575): +2M

Command (m for help): p

Disk /dev/hda: 16 heads, 63 sectors, 1575 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1         5      2488+  83  Linux
</verbatim>

<verbatim>
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (6-1575, default 6):
Using default value 6
Last cylinder or +size or +sizeM or +sizeK (6-1575, default 1575): +2M

Command (m for help): p

Disk /dev/hda: 16 heads, 63 sectors, 1575 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1         5      2488+  83  Linux
/dev/hda2             6        10      2520   83  Linux
</verbatim>

<verbatim>
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (11-1575, default 11):
Using default value 11
Last cylinder or +size or +sizeM or +sizeK (11-1575, default 1575): +64M

Command (m for help): t
Partition number (1-4): 3
Hex code (type L to list codes): 82
Changed system type of partition 3 to 82 (Linux swap)

Command (m for help): p

Disk /dev/hda: 16 heads, 63 sectors, 1575 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1         5      2488+  83  Linux
/dev/hda2             6        10      2520   83  Linux
/dev/hda3            11       141     66024   82  Linux swap
</verbatim>

Note that we had to use the =t= command to mark this
partition as swap space.

<verbatim>
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 4
First cylinder (142-1575, default 142):
Using default value 142
Last cylinder or +size or +sizeM or +sizeK (142-1575, default 1575):
Using default value 1575

Command (m for help): p

Disk /dev/hda: 16 heads, 63 sectors, 1575 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hda1             1         5      2488+  83  Linux
/dev/hda2             6        10      2520   83  Linux
/dev/hda3            11       141     66024   82  Linux swap
/dev/hda4           142      1575    722736   83  Linux
</verbatim>


<verbatim>
Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
 hda: hda1 hda2 hda3 hda4
 hda: hda1 hda2 hda3 hda4

WARNING: If you have created or modified any DOS 6.x
partitions, please see the fdisk manual page for additional
information.
Syncing disks.
</verbatim>

Now we are ready to initialize the partitions:

<verbatim>
# mkswap /dev/hda3
Setting up swapspace version 1, size = 67604480 bytes
# mke2fs /dev/hda4
mke2fs 1.19, 13-Jul-2000 for EXT2 FS 0.5b, 95/08/09
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
90432 inodes, 180684 blocks
9034 blocks (5.00%) reserved for the super user
First data block=0
6 block groups
32768 blocks per group, 32768 fragments per group
15072 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840

Writing inode tables: done
Writing superblocks and filesystem accounting information: done
</verbatim>