Re: Should Pstore(ramoops) records customized information?

[Zhang, Yanmin]

On 2014/6/25 21:08, Liu hua wrote:
> ä 2014/6/25 8:41, Zhang, Yanmin åé:
> > On 2014/6/20 18:47, Liu hua wrote:
> > > On 2014/6/20 7:42, Luck, Tony wrote:
> > >
> > > > > BTW, I note that "extern struct pstore_info *psinfo" locates in
> > > > > fs/pstore/internal.h. So users out of directory "fs/pstore/" can not use pstore to
> > > > > record messages. We do not want other kernel users to use pstore, right?  And can we
> > > > > break this?
> > > > Yes we can make some interface visible to the rest of the kernel ... probably
> > > > not the raw "*psinfo" though. Perhaps the pstore_alloc_ring_buffer() and
> > > > pstore_write_ring_buffer() functions should be the ones exported to the
> > > > rest of the kernel.
> > > >
> > > > > ditoo.. Since other backends like efi and erst may can not privide such ring buffer.
> > > > > So pstore_alloc_ring_buffer should be a funciton pointer of pstore_info struct.
> > > > Yes - that allows less capable backend like ERST and efivars to not provide the
> > > > service.  Since it becomes internal, you can drop the "pstore_" prefix.  E.g.
> > > > something like:
> > > >
> > > > int pstore_alloc_ring_buffer(char *name, int size)
> > > > {
> > > >      return psinfo->alloc_ring_buffer(name, size);
> > > > }
> > > > EXPORT_SYMBOL_GPL(pstore_alloc_ring_buffer);
> > > >
> > > > ... and you have to find/make some global header for the "extern" declaration.
> > > I will make these RFC patch series according to our discussion. Thanks you very to
> > > valuable advice.
> > Sorry for seeing your email late.We already worked out some patches to restructure
> > pstore. Would you like to try patchset http://article.gmane.org/gmane.linux.kernel/1697680/?
> >
> > We have more patches available to add some flags to disable/enable specific zones.
> That's great! I have tried your patches. BTW, Your patches do not work on ARM platform,
> before I changed linker scripts;

Initially, we just implemented it on x86. It's easy to extend it to ARM. Mostly change the arm
vmlinux.lds.S to add the sections. Pls. also change setup_arch to allocate memory blocks for
pstore.
In the patchset, there is an example patch, including reserve memory and zone examples.
Pls. reference it.

>   And can we use this method in modules(I failed to do that)?

It's a good question. There are many approaches to support modules.
1) Define the zone in built-in files and export it.Then, you can use it in module.
2) Define the zone and new tracer functions in built-in files and export
the tracer functions.

> After a quick glance and try, I think my idea is a little different from yours. I will reply you
> later.

Pls. Share your opinions. We are improving pstore to make it easier to be used.

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