On Thu, Sep 4, 2014 at 4:19 PM, Henrique de Moraes Holschuh <hmh@xxxxxxxxxx> wrote: > On Thu, 04 Sep 2014, H. Peter Anvin wrote: >> On 09/04/2014 01:11 PM, Henrique de Moraes Holschuh wrote: >> > I am worried of uncharted territory, here. I'd actually advocate for not >> > enabling the upper four PAT entries on IA-32 at all, unless Windows 9X / XP >> > is using them as well. Is this a real concern, or am I being overly >> > cautious? >> >> It is extremely unlikely that we'd have PAT issues in 32-bit mode and >> not in 64-bit mode on the same CPU. > > Sure, but is it really a good idea to enable this on the *old* non-64-bit > capable processors (note: I don't mean x86-64 processors operating in 32-bit > mode) ? > >> As far as I know, the current blacklist rule is very conservative due to >> lack of testing more than anything else. > > I was told that much in 2009 when I asked why cpuid 0x6d8 was blacklisted > from using PAT :-) At the very least, anyone who plugs an NV-DIMM into a 32-bit machine is nuts, and not just because I'd be somewhat amazed if it even physically fits into the slot. :) --Andy > > -- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>