Re: Support for CXL v3.0 spec with QEMU

[Ira Weiny <ira.weiny@intel.com>]

Ravi Kanth wrote:
> Hi Jonathan / Gregory,
> Just wanted to touch base on below questions and if you have any
> inputs on the same. Thanks for your help.
> 
> Thanks
> Ravi
> 
> On Wed, Oct 18, 2023 at 4:00 PM Ravi Kanth <mvrravikanth@gmail.com> wrote:
> >
> > Hi Jonathan / Gregory,
> >
> > 1. Do we have the support in CXL driver to read the "Device status
> > registers" and specifically "Event status register" section 8.2.8.3
> > and 8.2.8.3.1?

Yes the upstream driver reads this when processing the Event interrupt
from the device.  Then it uses the value to chose which logs to read.

See cxl_event_thread() in the kernel source.

> > 2. If an interrupt is posted by the device firmware, how will user
> > space applications be notified ? Do we have an interface for the same
> > in CXL driver?

All events are reported through the trace infrastructure.

> >
> > If the above features are already supported in CXL driver, Can you
> > please point us to the sample code snippets to achieve the same?

ndctl has the ability to monitor these events and example C code in there.

See .../cxl/event_trace.c in the ndctl project.[1]

[1] https://github.com/pmem/ndctl

> >
> > Also does the switch cci function change part of the mainline?

I'm not sure I parse this question but I'm also not super familiar with
switch cci.  So I'll let Jonathan answer this.

Ira

> >
> > Thanks for your help in advance.
> >
> > Thanks
> > Ravi
> >

[snip]