On Fri, Dec 07, 2012 at 11:38:11AM -0600, Scott Wood wrote:
On 12/07/2012 10:58:53 AM, Phil Sutter wrote:
Scott,
On Fri, Dec 07, 2012 at 12:53:34PM +0100, Phil Sutter wrote:
On Thu, Dec 06, 2012 at 12:18:39PM -0600, Scott Wood wrote:
On 11/28/2012 03:06:00 PM, Phil Sutter wrote:
Hi,
On Tue, Nov 27, 2012 at 04:04:15PM -0600, Scott Wood wrote:
On 11/21/2012 06:59:19 AM, Phil Sutter wrote: > Without this patch, when the currently chosen environment
to be
> written > has bad blocks, saveenv fails completely. Instead, when
there is
> redundant environment fall back to the other copy.
Environment
reading
> needs no adjustment, as the fallback logic for incomplete
writes
> applies > to this case as well. > > Signed-off-by: Phil Sutter phil.sutter@viprinet.com
Isn't this what CONFIG_ENV_RANGE is supposed to deal with?
Yes, that is more or less what is supposed to help for cases
like
this. But given the fact that CONFIG_ENV_RANGE needs to span multiple
erase
pages which in our case are 128k in size, this is quite a deal. Especially since one needs to have multiple pages for both
normal and
redundant environment to be really sure.
And *that* is what CONFIG_ENV_OFFSET_OOB is supposed to deal
with. :-)
Good to know, I already wondered what exactly this option is there
for.
Hmm. Does not look like CONFIG_ENV_OFFSET_OOB is used to select the block(s) within the erase page to save the environment. Looking at common/env_nand.c:318, the environment offset saved in the OOB seems to be in erase page unit.
I'm not sure what you mean by "block(s) within the erase page" -- blocks are the unit of erasing, and of bad block marking.
Not always, at least not with NAND flash. Erase pages are mostly bigger than write pages (or "blocks"). In my case, flash consists of 0x800 bytes write pages and 0x2000 bytes erase pages.
The block to hold the environment is stored in the OOB of block zero, which is usually guaranteed to not be bad.
Erase or write block? Note that every write block has it's own OOB.
On the other hand, I could not find code that alters this setting based on bad blocks found or whatever. This seems to simply be an alternative to setting CONFIG_ENV_OFFSET at build-time.
It is set by the "nand env.oob" command. It is currently a manual process (or rather, automation is left to the user's board preparation process rather than being built into U-Boot), as U-Boot wouldn't know how to give back unused blocks to other purposes.
So that assumes that any block initially identified 'good' will ever turn 'bad' later on?
Best wishes,
Phil Sutter Software Engineer