Re: [PATCH v9 8/8] ABI: sysfs-bus-pci: add documentation for p2pmem allocate

From: John Hubbard <jhubbard@nvidia.com>
To: Logan Gunthorpe <logang@deltatee.com>,
	linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-mm@kvack.org
Cc: "Christoph Hellwig" <hch@lst.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Christian König" <christian.koenig@amd.com>,
	"Don Dutile" <ddutile@redhat.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Minturn Dave B" <dave.b.minturn@intel.com>,
	"Jason Ekstrand" <jason@jlekstrand.net>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Xiong Jianxin" <jianxin.xiong@intel.com>,
	"Bjorn Helgaas" <helgaas@kernel.org>,
	"Ira Weiny" <ira.weiny@intel.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Martin Oliveira" <martin.oliveira@eideticom.com>,
	"Chaitanya Kulkarni" <ckulkarnilinux@gmail.com>,
	"Ralph Campbell" <rcampbell@nvidia.com>,
	"Stephen Bates" <sbates@raithlin.com>
Subject: Re: [PATCH v9 8/8] ABI: sysfs-bus-pci: add documentation for p2pmem allocate
Date: Mon, 5 Sep 2022 18:03:59 -0700	[thread overview]
Message-ID: <082bfb32-be2a-0fc4-6818-2730e904c000@nvidia.com> (raw)
In-Reply-To: <20220825152425.6296-9-logang@deltatee.com>

On 8/25/22 08:24, Logan Gunthorpe wrote:
> Add documentation for the p2pmem/allocate binary file which allows
> for allocating p2pmem buffers in userspace for passing to drivers
> that support them. (Currently only O_DIRECT to NVMe devices.)
> 
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
> ---
>  Documentation/ABI/testing/sysfs-bus-pci | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> index 6fc2c2efe8ab..dca5e032b4fa 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -171,7 +171,7 @@ Description:
>  		binary file containing the Vital Product Data for the
>  		device.  It should follow the VPD format defined in
>  		PCI Specification 2.1 or 2.2, but users should consider
> -		that some devices may have incorrectly formatted data.  
> +		that some devices may have incorrectly formatted data.
>  		If the underlying VPD has a writable section then the
>  		corresponding section of this file will be writable.
>  
> @@ -407,6 +407,16 @@ Description:
>  	        file contains a '1' if the memory has been published for
>  		use outside the driver that owns the device.
>  
> +What:		/sys/bus/pci/devices/.../p2pmem/allocate
> +Date:		August 2022
> +Contact:	Logan Gunthorpe <logang@deltatee.com>
> +Description:
> +		Thes attribute allows mapping p2pmem into userspace. For

s/Thes/This/

Actually, the sentence goes on to say "file", which refers to the same
thing as "attribute". So maybe just saying "This attribute" would be
slightly clearer? So:

		This file allows mapping p2pmem into userspace. For

With the typo fix and optionally the "attribute" change (up to you),
please feel free to add:

Reviewed-by: John Hubbard <jhubbard@nvidia.com>

thanks,

-- 
John Hubbard
NVIDIA

> +		each mmap() call on this file, the kernel will allocate
> +		a chunk of Peer-to-Peer memory for use in Peer-to-Peer
> +		transactions. This memory can be used in O_DIRECT calls
> +		to NVMe backed files for Peer-to-Peer copies.
> +
>  What:		/sys/bus/pci/devices/.../link/clkpm
>  		/sys/bus/pci/devices/.../link/l0s_aspm
>  		/sys/bus/pci/devices/.../link/l1_aspm