[U-Boot-Users] [PATCH]: Fix for bug: U-boot environment corrupt by reading uninitialized flash memory instead of RAM.

[Remy Bohmer]

Hello Wolfgang,

2008/5/9 Wolfgang Denk <wd at denx.de>:
> In message <3efb10970805060705l112c623at96bf0521eed8a211 at mail.gmail.com> you wrote:
>> Commit c0559be371b2a64b1a817088c3308688e2182f93 introduces a bug in
>> the environment setting storage in U-boot-1.3.3-rc3.
>> Settings are retrieved from dataflash when only settings in RAM are
>> valid, resulting in corrupt environment settings, failing printenv
>> command, and
>> duplicate variables.
>> This patch fixes this by always using the RAM area when it is created
>> and initialized. (Matches more the behavior as it was prior to this
>> particular commit.)
> Sorry, but this patch makes littles sense to me.

If you do not like the way it is fixed, then remove git-commit
c0559be371b2a64b1a817088c3308688e2182f93 which causes this regression
for the time being, to buy more time to fix it in a different/better
way for the next release. Now with this commit the complete at91-board
series (boards that boot from dataflash or nandflash) are broken.
So,we have a serious regression here.

BTW: If you look at the code _before_ commit
c0559be371b2a64b1a817088c3308688e2182f93 you will see that immediately
when the gd->env_valid is set to 1, _always_ the memory routines are
used to read the environment settings. It has been that for many
years. Commit c0559be371b2a64b1a817088c3308688e2182f93 changes this
behavior, although it suggests that it only would change the use of
early global variables. Notice that this commit is more like a
cosmetic change, so it would do no harm to leave it out until the next
release.
With my patch I tried to get this old behavior back in the tree, and
therefor it should work properly for other boards as well. Even if it
sounds redundant.

>> See attached (Sorry, my mailer does not handle inline-patches properly)
> Chose another one? Or rather use "git-send-email" directly?

Stuck to company rules, and from behind a http-proxy, which blocks
this kind of traffic? No way is that going to work...

> Let's keep in mind that the normal logic of the U-Boot startup
> sequence is like this:
> * U-Boot boots and initializes the RAM

Nope, not on AT91 with dataflash (or nandflash) boot...
AT91Bootstrap is used to initialize the RAM, copies the U-boot code
from serial dataflash (SPI bus) to RAM, and then starts executing
U-Boot.

> * U-Boot relocates itself into RAM, sets GD_FLG_RELOC and continues
>  running from RAM

U-boot will not _relocate_ itself in RAM, because it is already there.
CONFIG_SKIP_RELOCATE_UBOOT is set for these boards, so GD_FLG_RELOC is
never set.

> * U-Boot continues with the initialization, for xample by setting up
>  the malloc arena, loading the working copy of the environment into
>  RAM (after which it set's gd->env_valid), etc.
> So the relocation to RAM always preceeds any use of malloc() and the
> setting of gd->env_valid. Or, put the other way round, we always set
> GD_FLG_RELOC long before gd->env_valid get's set.
> Thus your change above is just redundant.

Not on AT91, because GD_FLG_RELOC is never set on AT91.

> Now, if your board  does  not  perform  proper  relocation  for  some
> reason, it should still set GD_FLG_RELOC at the appropriate place, i.
> e. as soon as U-Boot is ready for and starts running out of RAM.

Figuring this out would take some time, and if you want to freeze
1.3.3 in the mean time, I would suggest to leave this commit out until
there is a proper fix for this regression. I can start looking at it
again next week, maybe Stelian (who created the AT91 board support in
the first place) is faster than me...


Kind Regards,

Remy