RouterBOOT on RB450G has a 4MB NAND kernel size limit

[Warner Losh]

On Mar 8, 2012, at 5:24 PM, Juli Mallett wrote:

> Hey folks,
> 
> I thought it might be useful to share this with others, so they don't
> waste 6 hours diffing ELF files trying to figure out what the problem
> is.
> 
> It turns out that although it can load ELF files of variable size over
> TFTP, and although the system is configured with a larger kernel NAND
> partition, RouterBOOT seems to choke (without any clear error, mind
> you, because that would be gratuitously-sensible) on loading kernels
> larger than 4MB.  Of course, it's hard to figure this out because
> nothing useful turns up on a quick search for '"setting up elf
> image..." hang' or '"setting up elf image..." -"setting up elf
> image... ok"', although once you figure it out, it's easy to confirm
> with a quick Google along the lines of 'rb450g 4mb kernel'.
> 
> So, be warned if you're thinking that you'll use an OpenWRT kernel
> with initramfs over netboot to provision devices to use FreeBSD by
> copying the kernel to NAND.  Or if you've got yaffs patches to your
> kernel and can just copy over kernels with impunity.
> 
> Has anyone looked at using U-Boot as a second stage loader on this
> hardware?  In order to make loader useful, we'd have to add an awful
> lot of infrastructure, including another yaffs implementation, when we
> don't even have one in-tree yet.  What would be most useful, too,
> would be to have MMC + SPI support in loader (here again, U-Boot is
> helpful), so that we could load kernels from SD.  That's a lot of work
> on loader, and U-Boot already does it all, right?  Any thoughts?

While not specifically for that hardware, I've scoped out the work it would take to port raj@'s work from ARM to MIPS.  It doesn't look huge, once you settle on the right 'syscall' model.  figured it would take a dedicated person in the weeks to months range of effort, depending on the person :).  Maybe semihalf has already done a port?

> (There is an MMC-over-SPI driver coming to the tree Real Soon Now, so
> booting FreeBSD from these things in production is actually quite
> trivial, if you can solve the kernel loading dilemma.)

Cool!

Warner

> Yours in frustration with Mikrotik,
> Juli.
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