[OpenWrt-Devel] [PATCH] brcm47xx: image: build alternative TRX using less, optimized LZMA

Stephen G. Parry sgparry at mainscreen.com
Sun Oct 12 16:30:42 EDT 2014

Hi All,
Apologies for bringing this up so long after the original post - I've
been out of circulation for a while after having bricked my WNR3500L.

My one problem with this patch is I would like to use it for initramfs
builds too. I will propose a patch shortly.

Using a no-dictionary lzma and no loader seems to make my builds to
flash and boot reliably - whereas with the default full compression and
loader, any given build has 50/50 chance whether it will successfully
flash and then boot. This is repeatable but not predictable, i.e. if a
given build flashes and boots once, it flashes every time. If it
doesn't, it never flashes, but I cannot see any pattern to what
distinguishes a successful image from a failure. I am not certain, but
it may even vary between different examples of the same model of router!
I had one image that failed with the router I bricked, but worked first
time with the replacement. Go figure?!!!

The difference between a working image and non-working image has been as
little as including extra kernel codepage modules (e.g. 437, utf-8) in
the build. I have not had time to determine if the code pages are
relevant or whether it's just a size problem.

For failed images, the symptoms vary depending on how I do the flash. If
I use a trx and flash using mtd command, on reboot I get "starting
program" then nothing. If I create a chk and flash using tftpd, on
reboot I get "LZMA boot" then "file too big".

It does not help that there are four or five ways of flashing an image
to my router (CFE tftpd, CFE flash command, stock GUI, stock mtd
command, openwrt gui, openwrt mtd command etc.), none of which are

The image I am trying to use is a minimal initramfs build (I am using
this as a kexec boot loader for the main kernel on external storage).
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