Re: Using reblob to load another blob from ram

[Erik M. <er...@bi...>]

On Thu, Apr 27, 2006 at 08:55:23PM +0200, Stefan Schmidt wrote:
> I'm not sure if i'm wrong here, because this is cvs-commit list and
> not discussion.

Well, yeah, it's used for discussion as well.

> I'm writing here becuase the lart ml seems to be broken for at least 3
> weeks. BTW, lart ml archive and anon cvs access to blob cvs is broken,
> too. So no really good starting point for hacking on blob.

AnonCVS breakage is due to SF.net breakage. It's supposed to be fixed
Real Soon Now [tm]: https://sourceforge.net/docs/A04/#cvs .

I finally managed to upload my SSH key and get cvssuck to mirror the
CVS repository. See http://cvs.m17n.org/~akr/cvssuck/ . It's rather
slow however. Using cvsconnect to cache the connection speeds things up
but creates empty repositories so I'm back at cvssuck alone. When
that's done, I'll try to generate a GIT archive from the CVS repository
using Keith Packard's parsecvs (git-cvsimport barfs over certain
branches). It works quite well for other CVS repositories I tried, so I
guess it will manage to import blob CVS as well.

> OK, back to my main problem. I'm one of the developer behind the
> http://openezx.org/ project. EZX is the name of the Motorola Linux
> smartphone architecture based on pxa27x. On this phones they use blob
> as bootloader. But we like to extend blob to choose the kernel to boot
> and booting kernel from MicroSD/SD card. This would help us a lot in
> kernel and userspace development because we don't need to touch the
> pre-installed system.
> 
> In some small talk with Tim Riker on IRC he suggested me to load
> the extended blob into ram and do a reblob. Sounds great, but 
> unfortunately i get it not working.
> 
> Some more words about the setup. Motorola had modified blob. After
> some discussion i was able to get the source. You can find it here:
> 
> http://www.datenfreihafen.org/~stefan/EZX/a780-blob.tar.bz2
> 
> It based on blob-2.0.5-pre2 .
> 
> We are able to communicate with the bootloader over usb. Harald Welte
> wrote some kind of bootloader client which is called boot_usb.
> 
> http://svn.gnumonks.org/trunk/a780/src/boot_usb/
> 
> It loads the code into ram, exactly to KERNEL_RAM_BASE, and afterwards
> JUMP to it. This works fine for selfcompiled kernels. But it does not
> work for the blob binary at the moment.
> 
> A compile of the modified blob source give me the the following
> interesting binaries:
> 
> blob
> blob-chain
> blob-rest
> blob-rest-elf32
> blob-start
> blob-start-chain
> blob-start-chain-elf32
> blob-start-elf32

Everything -elf32 is the ELF32 version of the target. However, that
can't be used to start the machine, so we use objcopy to generate a
binary image. So: blob-start-elf32 --> (objcopy) --> blob-start .

Note the current CVS version uses a different way to build cause we use
the linker to link the second stage loader: we tell ld to generate an
.o file from blob-rest and link that into the first stage loader.

> I tried all of them load to KERNEL_RAM_BASE and also to BLOB_RAM_BASE
> as defined inside the blob code.

Right now there are four targets:

- blob-rest-elf32
- blob-rest
- blob-elf32
- blob

> If i load blob or blob-start-elf32 the display goes blank and thats
> it. For blob-start at KERNEL_RAM_BASE it goes blank, too. On all the
> other tests exactly nothing happens.

You should be able to reblob the second stage loader (i.e.: blob-rest).
It should be loaded at BLOB_RAM_BASE.

> I just changed the version string displayed to confirm if i see the
> new blob on the screen.
> 
> So perhaps anybody here can help me at this point. The most
> interesting questions are the following:
> 
> - Is there some good doc about blob? I don't find anything.

The source and the README is all there is.

> - Which binary i had to use for reblob?

blob-rest.

> - Which place i had to load into ram? BLOB_RAM_BASE or
>   KERNEL_RAM_BASE?

BLOB_RAM_BASE.

> - Tim Riker mentoined there are flying some SD card patches around.
>   Where can i find it?

I don't know about them. There is however some SD support in the
kernel.


Erik

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