On Tue, Feb 17, 2015 at 12:42 AM, Boaz Harrosh <b...@plexistor.com> wrote: > On 02/17/2015 12:03 AM, Matthew Wilcox wrote: >> On Mon, Feb 16, 2015 at 01:07:07PM +0200, Boaz Harrosh wrote: >>> In any way this is a problem for the new type-12 NvDIMM memory chips that >>> are circulating around. (It is estimated that there are already 100ds of >>> thousands NvDIMM chips in active use) >> >> Hang on. NV-DIMM chips don't know anyhing about E820 tables. They don't >> have anything in them that says "I am type 12!". How they are reported >> is up to the BIOS. Just because your BIOS vendor has chosen to report >> tham as type 12 doesn't mean that any other BIOS vedor is going to have >> done the same thing. >> >> Fortunately, the BIOS people have all got together and decided what >> they're going to do, and it's not type 12. Unfortunately, I think >> I'm bound by various agreements to not say what they are going to do >> until they do. But putting this temporary workaround in the kernel to >> accomodate one BIOS vendor's unreleased experimental code seems like >> entirely the wrong idea. >> > > I had a feeling I'm entering an holy war ;-). > > I hope you are OK with my first patch. That an unknown type need not > be reported busy, and behave same as "reserved"?
No, it seems the safe thing to do is prevent the kernel from accessing any memory that it does not know the side-effects of accessing. > Then if we agree about PATCH-1, which is the actual fix. > Then the 2nd patch (hence the RFC btw) is nothing more than > a name. > > I have an old BIOS that knows nothing of NvDIMM, actually a few > of them they all report 12. > The fact of the matter is that all the people I've talked with, > reported that different vendor chips, all came up type-12. > Perhaps type-12 just means "Unknown to current BIOS" > > What is the name you suggest "type-12" "unknown-12". > Do you understand why they all come out 12 ? > In fact it was originally "type-6" until ACPI 5 claimed that number for official use, so these platforms, with early proof-of-concept nvdimm support, have already gone through one transition to a new number. They need to do the same once an official number for nvdimm support is published. Put another way, these early platforms are already using out-of-tree patches for nvdimm enabling. They can continue to do so, or switch to standard methods when the standard is published. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
