Re: [GIT preview] for-6.3/cxl-ram-region

[Dan Williams <dan.j.williams@intel.com>]

Gregory Price wrote:
> On Mon, Jan 30, 2023 at 12:10:08PM -0800, Dan Williams wrote:
> > Gregory Price wrote:
> > [..]
> > > I found the same results.
> > > echo mem0 > /sys/bus/cxl/devices/region0/target0
> > > 
> > > Not sure if bug/missing feature, but after attaching a device to the
> > > target, you get no output when reading target0
> > > 
> > > ```
> > > [root@fedora ~]# cat /sys/bus/cxl/devices/region0/target0
> > > 
> > > [root@fedora ~]#
> > 
> > Hmm, did you not get:
> > 
> > "-bash: echo: write error: Invalid argument"
> > 
> > ...at that step? Because targetX expects an endpoint decoder, not a
> > memdev.
> > 
> 
> ¯\_(ツ)_/¯ bug?
> 
> I went through the kernel code and thought it was looking for a memdev
> but i guess i was wrong
> 
> // ... snip ...
>     dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
>     if (!dev)
>       return -ENODEV;
> 
>     if (!is_endpoint_decoder(dev)) {
>       rc = -EINVAL;
>       goto out;
>     }
> // ... snip ...

Oh, yes, it is a bug. I fixed it up when I address this 0day report:

https://lore.kernel.org/linux-cxl/202301281313.kVrIreUj-lkp@intel.com/

...I posted another spin of that branch with that fixed up.