[U-Boot-Users] RFC: U-Boot Environment support in SystemAce Compact FLASH

[Andrew Dyer <amdyer@gmail.com>]

On 8/22/05, Wolfgang Denk <wd@denx.de> wrote:
> In message <OF8ADB0661.25EF292C-ON07257065.00568E7A-07257065.00576B05@mck.us.ray.com> you wrote:
> >
> > I have completed the initial port of U-Boot to a custom PPC405/VirtexII
> > Pro FPGA board and I am starting to look at ways to store the U-Boot
> > environment in the CF card used for FPGA configuration by the Xilinx
> > SystemAce.
> 
> Please re-read the archives why this is not as trivial as it may seem.
> 
> > I am leaning toward the approach of adding DOS FAT write support and
> > adjusting the initial U-Boot environment to provide sufficient stack space
> 
> This won't help you much. In the first step, you would have to modify
> the whole CF and DOS FAT code such that it works while  running  from
> flash.  This is a non-trivial task, and I don't intend to accept such
> modifications for inclusion in the publich tree.
> 

Does a system ace CF card have a partition table?  Maybe you could make a
special partition on the CF for this type of info.  You would need a sector read
routine and code to parse the partition table to index into the
environment sectors.
You would probably need some ram available (or at least a bunch of registers)
to pull this off.

Another option might be to store the environment stuff as data to be loaded into
an accessible block ram on fpga power-up.  I haven't looked at how system ace
handles this sort of thing.  Are the block ram contents stored in
separate files on
the CF?

-- 
Hardware, n.:
        The parts of a computer system that can be kicked.