[U-Boot-Users] dtb in env sector - was: (Try 2) Please pull ...

Joakim Tjernlund joakim.tjernlund at transmode.se
Tue Apr 3 17:14:25 CEST 2007

On Tue, 2007-04-03 at 10:21 -0400, Jerry Van Baren wrote:
> Joakim Tjernlund wrote:
> > On Tue, 2007-04-03 at 14:59 +0200, Wolfgang Denk wrote:
> >> In message <1175600261.12080.24.camel at gentoo-jocke.transmode.se> you wrote:
> >>> I think to start with one would just need an install dtb command that
> >>> places the dtb at the end of the env. sector to allow either one
> >>> to grow without trashing eachother. Also rendundant env needs to be
> >> Umm... The environment will not grow beyond it's defined  size.  Then
> >> just use "cp" to copy the dtb to the next free address.
> > 
> > And later you need some more space for env. so you increase CFG_ENV_SIZE
> > a little and now you have destroyed your dtb as well.
> Actually, it is much worse than that: currently when you do a "saveenv" 
> it will wipe out the fdt blob because it doesn't know that the blob is 
> in the same sector.

Oh, my memory from the good old days(ppcboot) was that saveenv copied 
the whole sector to RAM, modified env. parts and wrote the whole
block back. Probably I remember incorrectly.

> I'm thinking that we want to store the blob immediately after the env 
> variable storage _reserved area_ as a #define option (as a new #define 
> option? part of the CONFIG_OF_LIBFDT define?) and enhance the env 
> save/restore to do the blob too.  This would get us the redundancy and 
> we can cover it with a new (preferred?) or existing env CRC (not good?).

Not sure, havn't had time to think about it yet.

> >>> Secondly one needs someway of telling bootm where to find the dtb.
> >> You pass the address as an argument...
> > 
> > yes, but it would be handy to just say "use the dtb in my spare
> > env space", especially if you use rendundant env. so the right
> > one is selected.
> > 
> >  Regards
> >           Jocke
> Best regards,
> gvb

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