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Date:   Tue, 30 May 2023 19:18:22 -0700
From:   Luis Chamberlain <mcgrof@kernel.org>
To:     Ira Weiny <ira.weiny@intel.com>
Cc:     Davidlohr Bueso <dave@stgolabs.net>, LiuLele <liu.lele@qq.com>,
        dave.jiang@intel.com, Jonathan.Cameron@huawei.com,
        alison.schofield@intel.com, bhelgaas@google.com,
        bwidawsk@kernel.org, dan.j.williams@intel.com, helgaas@kernel.org,
        linux-acpi@vger.kernel.org, linux-cxl@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        rostedt@goodmis.org, vishal.l.verma@intel.com
Subject: Re: CXL memory device not created correctly
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On Fri, May 19, 2023 at 08:20:44AM -0700, Ira Weiny wrote:
> Davidlohr Bueso wrote:
> > On Fri, 19 May 2023, LiuLele wrote:
> > 
> > >In my testing CXL device /sys/bus/cxl/devices/mem0  not created, and the get error messages :
> > >
> > >```
> > >cxl_pci 0000:0d:00.0: Failed to get interrupt for event Info log
> > >```
> > >
> > >My test environment is a qemu CXL emulator with qemu v8.0.0, Linux kernel v6.3.0.
> > >While with kernel 5.9.13,  /sys/bus/cxl/devices/mem0  can be created.
> > 
> > Yes, this can be annoying and would argue the probe should not error out.
> 
> I had to double check.  Events are mandatory on devices.  On checking
> again interrupt support is mandatory as well.  So that is why I errored
> out here.

The failure essentially creates a user visible regression whereas
booting an older kernel fixes it. It is not a friendly error message
when testing kernels / upgrading / test environments. The only thing
I can think of is if a new kconfig symbol is introduced so to make
such cases a bit more clearer for now as things get settled.

Otherwise for testing this creates a few cycles of just noise. And I'd
imagine even a few developer hours.

  Luis