On Fri, Aug 11, 2023 at 02:40:45PM -0400, Alistair Francis wrote: > On Thu, Aug 10, 2023 at 9:04 PM Damien Le Moal <dlemoal@xxxxxxxxxx> wrote: > > > > On 8/11/23 01:33, Alistair Francis wrote: > > > The PCIe 6 specification added support for the Data Object Exchange (DOE). > > > When DOE is supported the Discovery Data Object Protocol must be > > > implemented. The protocol allows a requester to obtain information about > > > the other DOE protocols supported by the device. > > > > > > The kernel is already querying the DOE protocols supported and cacheing > > > the values. This patch exposes the values via sysfs. This will allow > > > userspace to determine which DOE protocols are supported by the PCIe > > > device. > > > > > > By exposing the information to userspace tools like lspci can relay the > > > information to users. By listing all of the supported protocols we can > > > allow userspace to parse and support the list, which might include > > > vendor specific protocols as well as yet to be supported protocols. > > > > > > Each DOE feature is exposed as a single file. The files are empty and > > > the information is contained in the file name. > > > > s/feature/protocol ? > > Fixed > > > > > Personally, I would still have each file content repeat the same information as > > the file name specifies. That is, file value == file name. That will avoid > > people getting confused as empty sysfs files are rather uncommon. > > I don't see an obvious way to implement that with the .show() > function. I don't see a clear way to know what file the user accessed. The show callback gets a pointer to the attribute it was called with, so you know the file that was opened and can figure it out from there as to what it should print out. I think right now it returns an error, right? That's not good as userspace is going to think "this attribute really isn't there if I can't read from it" as that is how all other sysfs files work. thanks, greg k-h
