On Wed, Nov 07, 2018 at 05:07:07PM +0100, Borislav Petkov wrote: > On Wed, Nov 07, 2018 at 07:38:56AM -0600, Bjorn Helgaas wrote: > > Firmware supplies ACPI namespace. The namespace contains an abstract > > description of the platform, including devices. Devices are > > identified by PNP IDs, which are analogous to PCI vendor/device IDs, > > except that a device may have several generic "compatible device IDs" > > in addition to an ID unique to the device. Devices may also contain > > methods (supplied by firmware as part of the namespace), which are > > essentially bytecode that can be executed by the ACPI interpreter in > > the kernel. Linux drivers claim ACPI devices based on PNP ID and > > operate them using either ACPI methods (which can decouple the driver > > from device specifics) or the usual direct MMIO/IO port/MSR style. > > > > Here's an outline of how it *could* work: > > > > - AMD defines "AMD0001" device ID for the CPU temp sensor > > - BIOS supplies AMD0001 devices in the ACPI namespace > > - Each AMD0001 device has a _TMP method (supplied by BIOS and > > specific to the CPU) > > - Linux driver claims AMD0001 devices > > - Driver reads temp sensors by executing _TMP methods (Linux ACPI > > interpreter runs the bytecode) > > Thanks for explaining. > > > That way when you release a new platform with different temp sensors, > > you update the BIOS AMD0001 devices and _TMP methods to know about > > them, and the old Linux driver works unchanged. > > So I don't know about temp sensors - I'm talking about amd_nb which is > something... well, I explained already what it is in my previous mail so > I won't repeat myself. > > Anyway, if there is such a PNP ID device - and I believe I have stumbled > upon some blurb about it in the BKDGs - which says "this device > represents the PCI device IDs of a CPU" and if that can be used to > register amd_nb through it, then sure, I don't see why not. > > This way, when new CPU comes out and the same PNP ID device is present, > amd_nb would load, sure. No, the idea was more that that temp monitoring, e.g., k10temp, could be independent of amd_nb. But I can tell this idea isn't going anywhere, so let's just forget that I stuck my neck out and let it die on the vine :) Bjorn
