[U-Boot] understanding mkimage a bit more

[Charles Krinke <charles.krinke@gmail.com>]

On Fri, May 6, 2011 at 10:33 AM, Gerhard Pircher
<gerhard_pircher@gmx.net> wrote:
>
> -------- Original-Nachricht --------
> > Datum: Fri, 6 May 2011 09:24:27 -0700
> > Von: Charles Krinke <charles.krinke@gmail.com>
> > An: u-boot at lists.denx.de
> > Betreff: [U-Boot] understanding mkimage a bit more
>
> > I can create a uImage with mkimage with "-C gzip" and it boots fine.
> > If I use "-C none", it hangs on boot with bootm in u-boot. The
> > arguments below come directly from the linux-2.6.35.12 kernel which
> > creates uImage from vmlinux.bin.gz (which is already compressed, I
> > know, but that is a different issue).
> >
> > In trying to work through how mkimage, uboot, objdump and objcopy
> > interact, my The question becomes "Why does a uImage created with -C
> > gzip boot with bootm and a uImage created with -C none hang?"
> >
> > In both
> > $ scripts/mkuboot.sh -A ppc -O linux -T kernel -C gzip -a 0x00000000
> > -e 0x00000000 -n Linux-2.6.35.12-svn438 -d ./vmlinux.bin.gz
> > /tftpboot/uImage
> > Image Name: ? Linux-2.6.35.12-svn438
> > Created: ? ? ?Fri May ?6 09:05:42 2011
> > Image Type: ? PowerPC Linux Kernel Image (gzip compressed)
> > Data Size: ? ?1714808 Bytes = 1674.62 kB = 1.64 MB
> > Load Address: 0x00000000
> > Entry Point: ?0x00000000
> >
> > $ scripts/mkuboot.sh -A ppc -O linux -T kernel -C none -a 0x00000000
> > -e 0x00000000 -n Linux-2.6.35.12-svn438 -d ./vmlinux.bin.gz
> > /tftpboot/uImage
> > Image Name: ? Linux-2.6.35.12-svn438
> > Created: ? ? ?Fri May ?6 09:10:31 2011
> > Image Type: ? PowerPC Linux Kernel Image (uncompressed)
> > Data Size: ? ?1714808 Bytes = 1674.62 kB = 1.64 MB
> > Load Address: 0x00000000
> > Entry Point: ?0x00000000
> > ckrinke at hwa:~/svn/trunk/linux-2.6.35.12$
> > ckrinke at hwa:~/svn/trunk/linux-2.6.35.12$
>
> You wrap a compressed kernel image in an uImage that is marked as
> 'uncompressed'. Thus U-Boot doesn't decompress the uImage and tries
> to directly execute the gzipped data. Decompress vmlinux.bin.gz with
> "gzip -d" before converting it with mkuboot.sh and it should work.
>
> regards,
> Gerhard
> --
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Dear Gerhard:

I appreciate your clue. That was the needed piece of information to
bootm an uncompressed kernel.

What I am working on is speeding up? the boot process of an MPC8323
design and this helps a bit.

The next issue is the flash file system. Normally, I like to use JFFS2
for reliability as embedded devices frequently have their power switch
turned off at any time. I do understand that UBIFS is getting more
prevalent lately and I wonder if you or anyone else has a comment on
the suitability of UBIFS in an environment where the power will be
turned off and on exexpectdly and frequently.

In googling UBIFS problems, I do see posts across the internet of
UBIFS devices that will not boot after power is turned off and on. My
experience with JFFS2 is that it has always recovered during boot with
all the designs I have participated in over the last several years.
Admiteddly, the act of doing something like "scandisk" on boot slows
the boot down, but does seem to add reliability.

--
Charles Krinke