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Date: Thu, 4 Apr 2024 09:44:22 +0100
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: fan <nifan.cxl@gmail.com>
CC: Davidlohr Bueso <dave@stgolabs.net>, <ira.weiny@intel.com>, Dave Jiang
	<dave.jiang@intel.com>, Fan Ni <fan.ni@samsung.com>, Navneet Singh
	<navneet.singh@intel.com>, Dan Williams <dan.j.williams@intel.com>, "Alison
 Schofield" <alison.schofield@intel.com>, Vishal Verma
	<vishal.l.verma@intel.com>, <linux-btrfs@vger.kernel.org>,
	<linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 08/26] cxl/mem: Expose device dynamic capacity
 capabilities
Message-ID: <20240404094422.00004a13@Huawei.com>
In-Reply-To: <ZgMUTq6HasHOiR15@debian>
References: <20240324-dcd-type2-upstream-v1-0-b7b00d623625@intel.com>
	<20240324-dcd-type2-upstream-v1-8-b7b00d623625@intel.com>
	<w4jkueqpvh7hzbywk42m7gxclg56nbgzhaqcgeb3q2b6dt3w6n@5vwicganqpsu>
	<ZgMUTq6HasHOiR15@debian>
Organization: Huawei Technologies Research and Development (UK) Ltd.
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On Tue, 26 Mar 2024 11:30:38 -0700
fan <nifan.cxl@gmail.com> wrote:

> On Mon, Mar 25, 2024 at 04:40:16PM -0700, Davidlohr Bueso wrote:
> > On Sun, 24 Mar 2024, ira.weiny@intel.com wrote:
> >   
> > > +What:		/sys/bus/cxl/devices/memX/dc/region_count
> > > +Date:		June, 2024
> > > +KernelVersion:	v6.10
> > > +Contact:	linux-cxl@vger.kernel.org
> > > +Description:
> > > +		(RO) Number of Dynamic Capacity (DC) regions supported on the
> > > +		device.  May be 0 if the device does not support Dynamic
> > > +		Capacity.  
> > 
> > If dcd is not supported then we should not have the dc/ directory
> > altogether.
> > 
> > Thanks,
> > Davidlohr   
> 
> I also think so. However, I also noticed one thing (not DCD related).
> Even for a PMEM device, for example, we have a ram directory under the
> device directory.

True, but it's new ABI so we don't have to copy and Dan's patch to
allow for hiding static attribute directories has landed in the meantime.
So I vote for hiding it.

> 
> ===================
> root@DT:~# cxl list
> [
>   {
>     "memdev":"mem0",
>     "pmem_size":536870912,
>     "serial":0,
>     "host":"0000:0d:00.0"
>   }
> ]
> root@DT:~# ls /sys/bus/cxl/devices/mem0/
> dc  dev  driver  firmware  firmware_version  label_storage_size  numa_node  payload_max  pmem  pmem0  ram  security  serial  subsystem	trigger_poison_list  uevent
> root@DT:~#
> ===================
> 
> Fan
>