On 03/11/2014 05:14 AM, James Bottomley wrote:
On Mon, 2014-03-10 at 21:52 +0100, Hannes Reinecke wrote:
On 03/10/2014 07:24 PM, James Bottomley wrote:
On Mon, 2014-03-10 at 15:28 +0100, Hannes Reinecke wrote:
EVPD page 0x83 is used to uniquely identify the device.
So instead of having each and every program issue a separate
SG_IO call to retrieve this information it does make far more
sense to display it in sysfs.
Christoph's suggestion of binary sysfs attributes for this rather than
the text ones you have is better ... because your current ones are going
to truncate when they run off the one page of data sysfs text attributes
get (i.e. about 2k of vpd).
Yes, I thought of that, too.
I thought to remember that binary attributes are reserved for
firmware/hardware-dependent interfaces.
If that's not the case I'll be moving to a binary attribute here.
Will be resending the patchset.
What should happen with the first patch in the series, then?
When moving to a binary attribute the first patch isn't required
anymore; should I drop it or send as a separate patch?
It can be applied separately.
I also still think we can get around the caching problem by requesting
the vpd page every time. Arrays will change it under us and the cache
will go stale. Even enclosures sometimes swallow unplug plug events and
simply change the vpd data.
Hmm. The whole idea of having the vpd data in sysfs is precisely so that
one does _not_ have to do I/O to access it.
I think using a flag to invalidate data would be better here.
And will keep Bart happy :-)
Will be updating the patchset.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
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