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> > > + > > > + return reserve_pfn_range(paddr, size, prot, 0); > > > > Nitty, but a pattern established by Liam which we've followed consistently > > in VMA code is to prefix parameters that might be less than obvious, > > especially boolean parameters, with a comment naming the parameter, e.g.: > > > return reserve_pfn_range(paddr, size, prot, /*strict_prot=*/0); > > Not sure I like that. But as this parameter goes away patch #8, I'll leave > it as is in this patch and not start a bigger discussion on better > alternatives (don't use these stupid boolean variables ...) ;) > > [...] > > > > + > > > +/** > > > + * pfnmap_track - track a pfn range > > > > To risk sounding annoyingly pedantic and giving the kind of review that is > > annoying, this really needs to be expanded, I think perhaps this > > description is stating the obvious :) > > > > To me the confusing thing is that the 'generic' sounding pfnmap_track() is > > actually PAT-specific, so surely the description should give a brief > > overview of PAT here, saying it's applicable on x86-64 etc. etc. > > > > I'm not sure there's much use in keeping this generic when it clearly is > > not at this point? > > Sorry, is your suggestion to document more PAT stuff or what exactly? > > As you know, I'm a busy man ... so instructions/suggestions please :) Haha sure, I _think_ the model here is to have a brief summary then underneath a more detailed explanation, so that could be: This address range is requested to be 'tracked' by a hardware implementation allowing fine-grained control of memory attributes at page level granularity. This allows for fine-grained control of memory cache behaviour. Tracking memory this way is persisted across VMA split and merge. Currently there is only one implementation for this - x86 Page Attribute Table (PAT). See Documentation/arch/x86/pat.rst for more details. > > > > > > + * @pfn: the start of the pfn range > > > + * @size: the size of the pfn range > > > > In what units? Given it's a pfn range it's a bit ambiguous as to whether it > > should be expressed in pages/bytes. > > Agreed. It's bytes. (not my favorite here, but good enough) Ack, definitely need to spell it out here! Cheers :) > > > -- > Cheers, > > David / dhildenb >