JDP : Flash

This is an old revision of Flash from 2004-06-09 14:44:39.

This is a guide how to make use of your flash unit in the javastation.

2.4 Kernel support for the flash simm

Download the patch http://www.dnd.utwente.nl/js/files/mtd-jsflash.diff and patch the kernel.Enable the following kernel options:

* Memory Technology Device (MTD) support* MTD partitioning support* Caching block device access to MTD devices* RAM/ROM/Flash chip drivers** Detect flash chips by Common Flash Interface (CFI) probe** Detect non-CFI AMD/JEDEC-compatible flash chips (< 2.4.22)** Detect JEDEC JESD21c compatible flash chips (2.4.22)** Support for AMD/Fujitsu flash chips* Mapping drivers for chip access** Sun Microsystems Javastation OS-flash support

And it is also recommended to enable character device access. It is needed to erase the flash and install a kernel image.

* Direct char device access to MTD devices

Compile, reboot and you should see something like this:

OS-flash: Found AMD AM29LV081OS-flash: Found 4 x8 devices at 0x0 in 32-bit modeOS-flash: Found 4 x8 devices at 0x400000 in 32-bit modeOS-flash: Found an alias at 0x800000 for the chip at 0x400000OS-flash: Found an alias at 0xc00000 for the chip at 0x0number of JEDEC chips: 2Creating 2 MTD partitions on "OS-flash":0x00000000-0x00080000 : "Bootstrap"0x00080000-0x00800000 : "Filesystem"

2.6 Kernel support for the flash simm

Download the patch http://www.dnd.utwente.nl/js/files/js-mtd-2.6.6.diff and patch the kernel.Enable the following kernel options:

* Memory Technology Device (MTD) support* MTD partitioning support* Caching block device access to MTD devices0* RAM/ROM/Flash chip drivers** Detect non-CFI AMD/JEDEC-compatible flash chips** Support for AMD/Fujitsu flash chips* Mapping drivers for chip access** Support non-linear mappings of flash chips** Sun Javastation userflash support

And it is also recommended to enable character device access. It is needed to erase the flash and install a kernel image.

* Direct char device access to MTD devices

Compile, reboot and you should see something like this:

OS-flash: Found AMD AM29LV081OS-flash: Found 4 x8 devices at 0x0 in 32-bit modeOS-flash: Found 4 x8 devices at 0x400000 in 32-bit modeOS-flash: Found an alias at 0x800000 for the chip at 0x400000OS-flash: Found an alias at 0xc00000 for the chip at 0x0number of JEDEC chips: 2Creating 2 MTD partitions on "OS-flash":0x00000000-0x00800000 : "OS-flash"0x00000000-0x00100000 : "Bootstrap"0x00100000-0x00800000 : "Filesystem"

Partitions

By default two partitions are created. This can be changed in drivers/mtd/maps/jsflash.c at line 120.

Filesystems

See [WhichFilesystemForFlash] to choose your filesystem.

Booting from flash

I assume we are building our bootable image in /tmp/flash.

Silo

Create an entry in etc/silo.conf in the image directory like this:

image = /boot/vmlinux.gz label=linux proll=/boot/proll.img append="root=/dev/mtdblock2"

Image

Create a tree with the following under /tmp/flash:

bootboot/vmlinux.gzboot/ieee32.bboot/second.bboot/proll.imgetcetc/silo.conf

Quick tips on how to reduce the size of your image* strip the kernel (strip --strip-all -R .note -R .comment)* compress the kernel with gzip* compress the proll gzip* compile your own second.b with all fs support but romfs ripped outGenerate a bootable rom-image:

# dd if=/dev/zero of=flash.img bs=1k count=1# genromfs -a 512 -f romfs.img -d /tmp/flash# cat romfs.img >> flash.img# rm -f romfs.img# losetup /dev/loop0 -o 1024 flash.img# mount -t romfs -o ro /dev/loop0 /mnt# silo -J flash.img -i /boot/ieee32.b -r /mnt# umount /mnt# losetup -d /dev/loop0

Copy the image to the flash simm:

# eraseall /dev/mtd/1# cp flash.img /dev/mtd/1

Done.JasperVanDerNeut