Skip to content

W
White Rabbit Switch - Software
Commit cb89756f authored by Alessandro Rubini's avatar Alessandro Rubini Committed by Federico Vaga
Browse files
Options

doc and patches: use software-ecc, with manual reinstall

parent 1158a698
Hide whitespace changes
Inline Side-by-side
Showing with 152 additions and 10 deletions
doc/wrs-build.in
View file @ cb89756f
......@@ -35,7 +35,7 @@
@setchapternewpage off
@set update-month August 2012
@set update-month October 2012
@finalout
......@@ -1249,11 +1249,153 @@ after boot:
@end example
If you are customizing the switch, you may use the
@file{flash_eraseall} and @file{cat} to replace individual parts of
@file{flash_erase} and @file{cat} to replace individual parts of
the system, like the kernel, or erase the @i{barebox} configuration to
restore the factory defaults. Note however that you shouldn't
modify the @i{dataflash} device (@code{/dev/mtd5}) unless you really
know what you are doing.
modify the @i{dataflash} device (@code{/dev/mtd4}) unless you really
know what you are doing (for example, the following chapter changes
it by using magic offsets in the commands).
@c ##########################################################################
@node Switching from HW-ECC to SW-ECC
@chapter Switching from HW-ECC to SW-ECC
After release 3.0 of this package we found that hardware ECC for NAND
memory is bugged in the CPU we are using. Thus, we'll soon have a new
release using software ECC, which however is not compatible, so a complete
reinstall will be needed.
As a ``quick and dirty'' solution to the reliability problem, to be
used before we develop and thoroughly test the new installation
procedure, you can take and installed switch and turn it to software
ECC support. The difference is in the ECC algorithms used by both
@i{barebox} and the kernel. So both need to be recompiled.
To recompile the kernel, just undefine @code{CONFIG_MTD_NAND_ATMEL_ECC_HW}
and define @code{CONFIG_MTD_NAND_ATMEL_ECC_SOFT} instead. To recompile
barebox, similary, just adapt the configuration. The new configurations,
for both @i{barebox} and the kernel, are included in this commit of
the repository.
The following services and files are prerequisites to run this update:
@itemize @bullet
@item An installed switch, that runs the older @i{barebox}.
@item A TFTP server, whence you can serve the kernel.
@item Optionally, the current kernel, using hardware ECC for NAND.
@item An NFS-Root installation (even a minimal one, with MTD tools).
@item The new barebox, using software ECC
@item The new kernel, using software ECC
@item An archive of the filesystem (unchanged from release 3.0).
@end itemize
An archive with all the pieces you'll need for this upgrade (and maybe
a little more than that) can be downloaded from the @i{files} section
of the @i{White Rabbit} project on @code{ohwr.org}. (However, the
archive doesn't include the filesystem image, which is big and didn't
change from release 3.0). The direct link is
@url{http://www.ohwr.org/attachments/download/1648/reflash-2012-10-09.tar.gz}
@sp 1
The manual steps for the upgrade, then, are the following ones:
@table @r
@item 1. Boot the switch using the TFTP script.
If your switch has been installed and the @i{dataflash}
is valid, you can boot it using the
@t{boot from TFTP script} menu entry. See @ref{Using wrboot}
for details. You don't need to access any NAND memory for this
to work (so even if it got corrupted, you'll be able to boot).
@item 2. Erase NAND.
Before switching to a different ECC model, you should erase
your NAND memory. All bits in erased blocks are set, so all
bytes are 0xff with either ECC convention. All areas used
by the system must be erased before switching to software ecc.
This means @t{/dev/mtd0}, @t{/dev/mtd1} and @t{/dev/mtd2}
(kernel, filesystem and barebox environment). This will forget
your local barebox configuration (e.g., MAC address).
@item 3. Boot again, with a new kernel
Run again the TFTP script to boot from NFS-Root, but using a
kernel that supports software ECC.
@item 4. Write the kernel and filesystem to flash
With this new kernel, you can write to NAND memory using software
ECC. @t{/dev/mtd0} will host the new kernel (the same you booted)
and @t{/dev/mtd1} will host the filesystem (unchanged from the
previous installation).
@item 5. Update barebox in data flash
The final step is updating barebox, so it can read and boot
the new kernel that is stored in flash with software ECC.
Barebox must be stored at offset 0x8400 of the SPI memory.
@end table
The following example shows step 2 (erasing flash):
@example
# flash_erase /dev/mtd0 0 0
Erasing 128 Kibyte @ 7e0000 -- 100 % complete
# flash_erase /dev/mtd1 0 0
Erasing 128 Kibyte @ 7fe0000 -- 100 % complete
# flash_erase /dev/mtd2 0 0
Erasing 128 Kibyte @ 20000 -- 100 % complete
@end example
The following example shows step 4 (writing the kernel and FS). You
can't just ``@t{cat zImage > /dev/mtd0}'' because NAND memory can only
be written in multiples of 512 bytes. So we'll add trailing unused
data to the zImage before writing to flash, and the final error can
be ignored. The final command (writing the filesystem) will take
50 seconds (uncompressing alone would take 18 seconds).
@example
# dd bs=1k count=1 < /dev/zero > /tmp/1k
1+0 records in
1+0 records out
# cat zImage-wrs3-swecc /tmp/1k | dd obs=512 > /dev/mtd0
nand_do_write_ops: Attempt to write not page aligned data
dd: writing 'standard output': Invalid argument
2886+1 records in
2886+0 records out
# mount -t jffs2 /dev/mtdblock1 /mnt
# cd /mnt
# zcat /path/to/your/copy/of/wrs-image.tar.gz | tar xf -
@end example
The following example shows step 5 (updating barebox). The block size
of the @i{dataflash} is 1056 bytes, and partial writes are supported
(unless what happens with NAND flash) so no padding is needed.
The command takes a few seconds to run:
@example
# cat barebox.bin-swecc | dd bs=1056 seek=32 > /dev/mtd4
182+1 records in
182+1 records out
@end example
@b{Hint}: at any time, if in doubt about what version of @i{barebox}
and the kernel you are running, you can check the date (@code{version}
in @i{barebox} and @code{uname -a} in Linux). Hardware-ECC images are
from August 2012 (official v3.0 release), while software-ECC images
are from October 2012. If you recompiled and are in doubt about
the kernel, you can @i{zgrep} for @code{ECC} in @code{/proc/config.gz}.
@c ##########################################################################
@node Schematics are Available
......
patches/barebox/wrs3_defconfig
View file @ cb89756f
......@@ -255,9 +255,9 @@ CONFIG_MTD=y
CONFIG_NAND=y
CONFIG_NAND_WRITE=y
CONFIG_NAND_ECC_SOFT=y
CONFIG_NAND_ECC_HW=y
CONFIG_NAND_ECC_HW_SYNDROME=y
CONFIG_NAND_ECC_HW_NONE=y
# CONFIG_NAND_ECC_HW is not set
# CONFIG_NAND_ECC_HW_SYNDROME is not set
# CONFIG_NAND_ECC_HW_NONE is not set
CONFIG_NAND_INFO=y
CONFIG_NAND_BBT=y
CONFIG_NAND_READ_OOB=y
......
patches/kernel/v2.6.39/linux-config-wrswitch
View file @ cb89756f
#
# Automatically generated make config: don't edit
# Linux/arm 2.6.39 Kernel Configuration
# Tue Aug 7 12:38:32 2012
# Tue Oct 9 11:41:20 2012
#
CONFIG_ARM=y
CONFIG_SYS_SUPPORTS_APM_EMULATION=y
......@@ -580,8 +580,8 @@ CONFIG_MTD_NAND=y
CONFIG_MTD_NAND_IDS=y
# CONFIG_MTD_NAND_DISKONCHIP is not set
CONFIG_MTD_NAND_ATMEL=y
CONFIG_MTD_NAND_ATMEL_ECC_HW=y
# CONFIG_MTD_NAND_ATMEL_ECC_SOFT is not set
# CONFIG_MTD_NAND_ATMEL_ECC_HW is not set
CONFIG_MTD_NAND_ATMEL_ECC_SOFT=y
# CONFIG_MTD_NAND_ATMEL_ECC_NONE is not set
# CONFIG_MTD_NAND_NANDSIM is not set
# CONFIG_MTD_NAND_PLATFORM is not set
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment