On Wed, Jan 06, 2021 at 01:31:46PM +0100, Hans de Goede wrote: > Hi All, > > I've 2 different kernel bugs where the fix requires differentiating between > Cherry Trail vs Brasswell, just checking the CPU model does not allow to > differentiate between these 2 since they are both using Airmont cores. > > I have the same issue with the Bay Trail laptop SoCs vs the > Bay Trail-T tablet SoCs, but for now lets focus on > Cherry Trail vs Brasswell since that is less confusing: > > https://ark.intel.com/content/www/us/en/ark/products/codename/46629/cherry-trail.html > https://ark.intel.com/content/www/us/en/ark/products/codename/66094/braswell.html > > So I see a number of possible solutions here: > > 1) Do a (substring) check on the CPU model-name checking for "x5-Z8" and "x7-Z8" > 2) Check for presence of some embedded peripheral which is present on one but not the > other. E.g. The Braswell devices have HDA audio where as the Cherry Trail devices > use the "Low Power Engine (LPE) Audio Controller" > 3) Check for acpi_gbl_reduced_hardware, but I'm not sure if that is a reliable > indicator of running on the tablet versions of the SoCs. > > 1 and 2 will work but neither is very pretty, I guess I could try to spend some > more time investigating 3. But I only have limited access to the non tablet versions > of the Bay Trail and I'm not sure if I have any Braswell devices at all. > > So I was wondering if anyone else has any better ideas here? Does MSR_PLATFORM_ID (0x17) bits 50-52 work to differentiate these?
