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From: Dan Williams <dan.j.williams@intel.com>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
	linux-cxl@vger.kernel.org, Linux PCI <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <helgaas@kernel.org>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Ben Widawsky <ben.widawsky@intel.com>,
	Chris Browy <cbrowy@avery-design.com>,
	Linux ACPI <linux-acpi@vger.kernel.org>,
	"Schofield, Alison" <alison.schofield@intel.com>,
	Vishal L Verma <vishal.l.verma@intel.com>,
	Linuxarm <linuxarm@huawei.com>, Fangjian <f.fangjian@huawei.com>
Subject: Re: [RFC PATCH v3 2/4] PCI/doe: Add Data Object Exchange support
Date: Fri, 14 May 2021 11:37:12 -0700
Message-ID: <CAPcyv4h_qSZq+sTAOTKDNsO3xPmq=65j8oO1iw0WdVFj8+XrOA@mail.gmail.com> (raw)
In-Reply-To: <20210514094755.00002081@Huawei.com>

On Fri, May 14, 2021 at 1:50 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
[..]
> > If it simplifies the kernel implementation to assume single
> > kernel-initiator then I think that's more than enough reason to block
> > out userspace, and/or provide userspace a method to get into the
> > kernel's queue for service.
>
> This last suggestion makes sense to me. Let's provide a 'right' way
> to access the DOE from user space. I like the idea if it being possible
> to run CXL compliance tests from userspace whilst the driver is loaded.

Ah, and I like your observation that once the kernel provides a
"right" way to access DOE then userspace direct-access of DOE is
indeed a "you get to keep the pieces" event like any other unwanted
userspace config-write.

> Bjorn, given this would be a generic PCI thing, any preference for what
> this interface might look like?   /dev/pcidoe[xxxxxx].i with ioctls similar
> to those for the BAR based CXL mailboxes?

(warning, anti-ioctl bias incoming...)

Hmm, DOE has an enumeration capability, could the DOE driver use a
scheme to have a sysfs bin_attr per discovered object type? This would
make it simliar to the pci-vpd sysfs interface.

Then the kernel could cache objects like CDAT that don't change
outside of some invalidation event.

  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-19 16:54 [RFC PATCH v3 0/4] PCI Data Object Exchange support + CXL CDAT Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 1/4] PCI: Add vendor ID for the PCI SIG Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 2/4] PCI/doe: Add Data Object Exchange support Jonathan Cameron
2021-05-06 21:59   ` Ira Weiny
2021-05-11 16:50     ` Jonathan Cameron
2021-05-13 21:20       ` Dan Williams
2021-05-14  8:47         ` Jonathan Cameron
2021-05-14 11:15           ` Lorenzo Pieralisi
2021-05-14 12:39             ` Jonathan Cameron
2021-05-14 18:37           ` Dan Williams [this message]
2021-05-17  8:40             ` Jonathan Cameron
2021-05-17  8:51               ` Greg KH
2021-05-17 17:21               ` Dan Williams
2021-05-18 10:04                 ` Jonathan Cameron
2021-05-19 14:18                   ` Dan Williams
2021-05-19 15:11                     ` Jonathan Cameron
2021-05-19 15:29                       ` Dan Williams
2021-05-19 16:20                         ` Jonathan Cameron
2021-05-19 16:33                           ` Jonathan Cameron
2021-05-19 16:53                             ` Dan Williams
2021-05-19 17:00                               ` Jonathan Cameron
2021-05-19 19:20                                 ` Dan Williams
2021-05-19 20:18                                   ` Jonathan Cameron
2021-05-19 23:51                                     ` Dan Williams
2021-05-20  0:16                                       ` Dan Williams
2021-05-20  8:22                                       ` Jonathan Cameron
2021-05-07  9:36   ` Jonathan Cameron
2021-05-07 23:10   ` Bjorn Helgaas
2021-05-12 12:44     ` Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 3/4] cxl/mem: Add CDAT table reading from DOE Jonathan Cameron
2021-04-19 16:54 ` [RFC PATCH v3 4/4] cxl/mem: Add a debug parser for CDAT commands Jonathan Cameron

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