Re: [PATCH v3 0/8] Nvram-to-pstore

From: Aruna Balakrishnaiah
Date: Wed Jun 05 2013 - 05:52:24 EST


On Wednesday 05 June 2013 03:13 PM, Benjamin Herrenschmidt wrote:
On Wed, 2013-06-05 at 14:30 +0530, Aruna Balakrishnaiah wrote:
Hi Ben,

On Saturday 01 June 2013 10:55 AM, Benjamin Herrenschmidt wrote:
Another question...

Should the core pstore fail to unlink partitions that don't have
an ->erase callback ? IE. Why would you let anyone erase the OFW
common partition for example ? That means that userspace tools
can no longer manipulate it but we certainly don't want to remove
it from the nvram itself.
Since I do not have a callback for erase in nvram, pstore
simply unlinks the file and will not delete the partition.
Right. My point is that it should probably refuse to unlink the file
too. What's the point in letting the user remove the file, potentially
making tools not working anymore, without any way to bring it back other
than a reboot ?

unlink makes sense if it also removes the partition. If it doesn't it
should just fail.

Right, makes sense. Will create a patch to fix it in pstore.

That leads to a deeper concern. Looking at how efi-pstore works,
it looks like they create a file for each var.

This looks like something valuable we could do for something like
the common partition since typically it's made of name,value pairs.

However, pstore is a flat space, while we have patitions which
themselves can be organized in name,value pairs (some at least)

I wonder if it's time to introduce pstore directories... Or do
we stick to our special tools to interpret/change the name,value
pairs ?
Since pstore infrastructure creates the file in read-only mode
creating files for name, value pairs will not be useful to us.
So for now, we need to stick to our tools to interpret/change
the name,value pairs.

And also, pstore filenames are controlled by pstore infrastructure
so that would need quite some changes in the pstore infrastructure.

I think for now it would be better to dump the contents of common
partition as it is.
Ok.

Also do we want to add an ability to resize partitions ? Possibly
based on how much is written to them ?
Yes it will be good to that.

If your fine with patchset apart from the filenames of-config and common
partitions. I will post the next version of it with powerpc prefix.
Yes, I'm ok with it.

Cheers,
Ben.

Cheers,
Ben.


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