From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-path: Date: Sat, 3 Nov 2018 00:29:48 +0100 From: Borislav Petkov To: Bjorn Helgaas Cc: "Woods, Brian" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "x86@kernel.org" , Clemens Ladisch , Jean Delvare , Guenter Roeck , Pu Wen , Jia Zhang , "linux-kernel@vger.kernel.org" , "linux-hwmon@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: [PATCH 2/4] x86/amd_nb: add support for newer PCI topologies Message-ID: <20181102232948.GC26770@zn.tnic> References: <20181102181055.130531-1-brian.woods@amd.com> <20181102181055.130531-3-brian.woods@amd.com> <20181102195925.GB160487@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181102195925.GB160487@google.com> List-ID: On Fri, Nov 02, 2018 at 02:59:25PM -0500, Bjorn Helgaas wrote: > This isn't my code, and I'm not really objecting to these changes, but > from where I sit, the fact that you need this sort of vendor-specific > topology discovery is a little bit ugly and seems like something of a > maintenance issue. You could argue that this is sort of an "AMD CPU > driver", which is entitled to be device-specific, and that does make > some sense. It is a bunch of glue code which enumerates the PCI devices a CPU has and other in-kernel users can use that instead of doing the discovery/enumeration themselves. > But device-specific code is typically packaged as a driver that uses > driver registration interfaces like acpi_bus_register_driver(), > pci_register_driver(), etc. That gives you a consistent structure > and, more importantly, a framework for dealing with hotplug. It > doesn't look like amd_nb.c would deal well with hot-add of CPUs. If you mean physical hotadd, then that's a non-issue as, AFAIK, AMD doesn't support that. Now, TBH I've never tried soft-offlining the cores of a node and then check whether using the PCI devices of that node would work. Now, I don't mind this getting converted to a proper PCI driver as long as it is not a module as it has to be present at all times. Other than that, I'm a happy camper. Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.