[FE training-materials-updates] Misc flash section improvements
Michael Opdenacker
michael.opdenacker at free-electrons.com
Thu Oct 29 07:49:46 CET 2015
Repository : git://git.free-electrons.com/training-materials.git
On branch : master
Link : http://git.free-electrons.com/training-materials/commit/?id=745506cb4381e66c9482cd925b9bae100bccb71c
>---------------------------------------------------------------
commit 745506cb4381e66c9482cd925b9bae100bccb71c
Author: Michael Opdenacker <michael.opdenacker at free-electrons.com>
Date: Thu Oct 29 07:49:46 2015 +0100
Misc flash section improvements
- In particular, warn about the limitations in BusyBox UBI tools,
which we use in the labs
Signed-off-by: Michael Opdenacker <michael.opdenacker at free-electrons.com>
>---------------------------------------------------------------
745506cb4381e66c9482cd925b9bae100bccb71c
.../sysdev-flash-filesystems.tex | 32 +++++++++++-----------
.../sysdev-flash-filesystems.tex | 27 +++++++++++++-----
2 files changed, 36 insertions(+), 23 deletions(-)
diff --git a/labs/sysdev-flash-filesystems/sysdev-flash-filesystems.tex b/labs/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
index 2799e7a..7d88d1b 100644
--- a/labs/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
+++ b/labs/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
@@ -76,7 +76,7 @@ not.
%
%
-% ubi config file content
+% ubi config file contents
%
%[kernel]
%mode=ubi
@@ -141,7 +141,7 @@ When flashing the UBI image, use the \code{trimffs} version of the
command \code{nand write}\footnote{The command \code{nand write.trimffs} skips
the blank sectors instead of writing them. It is needed because the
algorithm used by the hardware ECC for the SAMA5D3 SoC generates a
- checksum with bytes different of 0xFF if the page is blank. Linux
+ checksum with bytes different from \code{0xFF} if the page is blank. Linux
only checks the page, and if it is blank it doesn't erase it, but as
the OOB is not blank it leads to ECC errors. More generally it is
not recommended writing more than one time on a page and its OOB
@@ -159,9 +159,9 @@ UBI volumes and try to boot them. If it works, you can modify your
Set the \code{bootargs} variable so that:
\begin{itemize}
-\item The \code{mtdparts} environment variable content is passed to
- the kernel through cmdline\footnote{Remember you can tweak your
- \code{bootargs} using u-boot env variables before booting the kernel.
+\item The \code{mtdparts} environment variable contents are passed to
+ the kernel through \code{cmdline}\footnote{Remember you can tweak your
+ \code{bootargs} using U-Boot environment variables before booting the kernel.
To achieve that, create a \code{bootargs_base} variable where you
will store all the kernel parameters except the \code{mtdparts}
one. Then modify your \code{bootcmd} to append the \code{mtdparts}
@@ -180,11 +180,11 @@ data filesystem should be mounted read-write, allowing you to upload
data using the web server.
%Useful u-boot environment variables
-%mtdids=nand0=atmel_nand
-%mtdparts=mtdparts=atmel_nand:256k(bootstrap),512k(u-boot),256k(u-boot-env1),256k(u-boot-env2),-(UBI)
-%bootargs_base=console=ttyS0,115200 rootfstype=ubifs root=ubi0:root ip=dhcp ubi.mtd=4 ro
-%bootcmd=mtdparts; ubi part UBI; ubi readvol 0x21000000 kernel; ubi readvol 0x22000000 dtb; setenv bootargs $bootargs_base $mtdparts; bootz 0x21000000 - 0x22000000
-%flash=mtdparts; nand erase.part UBI; tftp 0x21000000 test.ubi; nand write.trimffs 0x21000000 UBI $filesize
+%setenv mtdids nand0=atmel_nand
+%setenv mtdparts mtdparts=atmel_nand:256k(bootstrap),512k(u-boot),256k(u-boot-env1),256k(u-boot-env2),-(UBI)
+%setenv bootargs_base console=ttyS0,115200 rootfstype=ubifs root=ubi0:root ip=dhcp ubi.mtd=4 ro
+%setenv bootcmd 'mtdparts; ubi part UBI; ubi readvol 0x21000000 kernel; ubi readvol 0x22000000 dtb; setenv bootargs $bootargs_base $mtdparts; bootz 0x21000000 - 0x22000000'
+%setenv flash 'mtdparts; nand erase.part UBI; tftp 0x21000000 test.ubi; nand write.trimffs 0x21000000 UBI $filesize'
\section{Going further}
@@ -193,8 +193,8 @@ data using the web server.
In some cases you might need to adapt your NAND partitioning without
re-flashing everything. Thanks to UBI this is possible.
-From Linux, resize the \code{data} volume to occupy the remaining
-space, and then create a new \code{log} volume of 16MiB. Mount this
+From Linux, resize the \code{data} volume to occupy 128 MiB,
+and then create a new \code{log} volume of 16MiB. Mount this
volume as a UBIFS filesystem and see what happens.
Update your init script to mount the UBI \code{log} volume on \code{/var/log}.
@@ -202,7 +202,7 @@ Reboot your system and check that the \code{log} is correcly mounted.
% Hints:
%
-%ubirsvol /dev/ubi0 -n 4 -s 50MiB
+%ubirsvol /dev/ubi0 -n 4 -s 128MiB
%ubimkvol /dev/ubi0 -N log -s 16MiB
%mount -t ubifs ubi0:log /var/log
%
@@ -224,7 +224,7 @@ the second kernel volume if the first one is corrupted:
it has finished and see what happens (unplug the platform)
\item Create a shell script to automate kernel updates (executed in Linux).
Be careful, this script should also handle the case where the backup
- volume has been corrupted (copy the content of the kernel volume into
+ volume has been corrupted (copy the contents of the kernel volume into
the backup one)
\end{itemize}
@@ -233,7 +233,7 @@ the second kernel volume if the first one is corrupted:
\subsection{Using {\em squashfs} for the root filesystem}
Root filesystems are often a sensitive part of your system, and you don't
-want it to be corrupted, hence some people decide to use read-only
+want it to be corrupted, hence some people decide to use a read-only
file system for their rootfs and use another file system to store their
auxiliary data.
@@ -245,7 +245,7 @@ of a static UBI volume to mount a {\em squashfs} filesystem as the
root filesystem:
\begin{itemize}
- \item First create a {\em squashfs} image with your rootfs content
+ \item First create a {\em squashfs} image with your rootfs contents
\item Then create a new static volume to store your squashfs and update it with
your squashfs image
\item Enable and setup the {\em ubiblk} layer
diff --git a/slides/sysdev-flash-filesystems/sysdev-flash-filesystems.tex b/slides/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
index d1528f0..1ca1876 100644
--- a/slides/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
+++ b/slides/sysdev-flash-filesystems/sysdev-flash-filesystems.tex
@@ -237,7 +237,7 @@
specified by the \code{mtdids} and \code{mtdparts} variables
\item Use flash specific commands (depends on your flash device type),
and pass partition names instead of numerical offsets
- \item Example: \code{nand erase <partname>}
+ \item Example: \code{nand erase.part <partname>}
\end{itemize}
\end{frame}
@@ -279,8 +279,8 @@ setenv mtdparts mtdparts=omap2-nand.0:512k(X-Loader)ro,1536k(U-Boot)ro,512k(Env)
\item \code{Kernel} (4 MiB)
\item \code{Root filesystem} (Remaining space)
\end{itemize}
- \item Partition sizes must be multiple of the erase block size.\\
- You can use sizes in hexadecimal too. Remember the below sizes:\\
+ \item Partition sizes must be multiple of the erase block size.
+ You can use sizes in hexadecimal too. Remember the below sizes:
\code{0x20000} = 128k, \code{0x100000} = 1m, \code{0x1000000} = 16m
\item \code{ro} lists the partition as read only
\item \code{-} is used to use all the remaining space.
@@ -669,8 +669,8 @@ vol_alignment=1
volume information if the \code{layout} string is passed
\item \code{ubi check <vol-name>} check if a volume exists
\item \code{ubi readvol <dest-addr> <vol-name> [<size>]} read volume
- content
- \item U-Boot also provides tools to update the UBI device content
+ contents
+ \item U-Boot also provides tools to update the UBI device contents
\item Using them is highly discouraged (the U-Boot UBI implementation
is not entirely stable, and using commands that do not touch the UBI
metadata is safer)
@@ -710,7 +710,7 @@ vol_alignment=1
\item \code{ubirmvol /dev/ubi<UBI-device-id> -N <name>} delete an UBI
volume
\item \code{ubiupdatevol /dev/ubi<UBI-device-id>_<UBI-vol-id> [-s <size>] <vol-image-file>}
- update volume content
+ update volume contents
\item \code{ubirsvol /dev/ubi<UBI-device-id> -N <name> -s <size>}
resize an UBI volume
\item \code{ubirename /dev/ubi<UBI-device-id>_<UBI-vol-id> <old-name> <new-size>}
@@ -719,6 +719,19 @@ vol_alignment=1
\end{frame}
\begin{frame}
+ \frametitle{Linux tools: BusyBox UBI limitations}
+ Beware that the implementation of UBI commands in BusyBox is still
+ incomplete. For example:
+ \begin{itemize}
+ \item \code{ubirsvol} doesn't support \code{-N <name>}. You have
+ to use specify the volume to resize by its id (\code{-n num}):\\
+ \code{ubirsvol /dev/ubi0 -n 4 -s 64 MiB}
+ \item Same constraint for \code{ubirmvol}:\\
+ \code{ubirmvol /dev/ubi0 -n 4}
+ \end{itemize}
+\end{frame}
+
+\begin{frame}
\frametitle{Linux: UBIFS host tools}
UBIFS filesystems images can be created using \code{mkfs.ubifs}
\begin{itemize}
@@ -854,7 +867,7 @@ vol_alignment=1
for data retention and wear leveling issues, while MTD does not)
\item The \code{ubiblock} layer creates {\bf read-only} block devices
on demand
- \item The user specifies which static volumes he would like to attach
+ \item The user specifies which static volumes (s)he would like to attach
to \code{ubiblock}
\begin{itemize}
\item Through the \code{cmdline}: by passing
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