Jonathan Cameron wrote:
> On Sun, 05 Feb 2023 17:02:45 -0800
> Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> > Shipping versions of the cxl-cli utility expect all regions to have a
> > 'uuid' attribute. In preparation for 'ram' regions, update the 'uuid'
> > attribute to return an empty string which satisfies the current
> > expectations of 'cxl list -R'. Otherwise, 'cxl list -R' fails in the
> > presence of regions with the 'uuid' attribute missing. Force the
> > attribute to be read-only as there is no facility or expectation for a
> > 'ram' region to recall its uuid from one boot to the next.
>
> This is new functionality, so do we need the backwards compatibility?
> Or does that cxl list -R not just skip these, but fail hard?
It does this:
# cxl list -R
libcxl: __sysfs_device_parse: region4: add_dev() failed
Warning: no matching devices found
[
]
...which in hindsight is not a helpful message. However, as an end user
I hate forced upgrades, so a small kernel behavior change to extend the
useful life of an installed tool is worthwhile.
> It's inelegant to have this visible at all (and it confused me when
> I was running tests as I assumed I needed to poke something in it).
It is RO to indicate that, but I do notice I neglected to update
Documentation/ABI/testing/sysfs-bus-cxl with this behavior.
>
> If nothing else, good to have a comment to remind us in the code
> why there is the oddity of setting it to read only.
Sure, I'll add that too.
