Hello Rob,

Sorry for the late reply ...

Rob Herring wrote:

On 12/06/2011 04:06 PM, Wolfram Sang wrote:

quoted

quoted

quoted

bootcount itself is not a device. It is a feature of certain devices. And that
needs to be implemented; possibly generic enough that it can work for register
based, i2c based, and so forth, accesses.

If "boot counter" is not a good name for such a device, then what name
would you suggest?

None.

quoted

Or do you think a counter (which can be implemented in a number of
different ways, depending on hardware specifics) is not a device?

Yes.

quoted

What would be such a device, then?

"maxim,ds1338"

Please have a look at the devicetree.org-wiki-page I just mentioned:

http://devicetree.org/Device_Tree_Usage

Perhaps fs/pstore would be a good choice for the user space interface
(defining a new file bootcount). This can support any arbitrary backing
device although pretty much only ACPI is implemented.

I tried to use fs/pstore for the bootcount feature, and I can mount
and read the bootcount value from the file, I created. But I could not
write to that file ... I only see the callback from
include/linux/pstore.h

struct pstore_info {
[...]
        int             (*write)(enum pstore_type_id type,
                        enum kmsg_dump_reason reason, u64 *id,
                        unsigned int part, size_t size, struct pstore_info *psi);

called, if I reboot ... do I miss something? Or is it not possible
to write to the files created through fs/pstore?

bye,
Heiko
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