| Message ID | 20180323081209.31387-6-oohall@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Mar 23, 2018 at 07:12:09PM +1100, Oliver O'Halloran wrote: > Add device-tree binding documentation for the nvdimm region driver. > > Cc: devicetree@vger.kernel.org > Signed-off-by: Oliver O'Halloran <oohall@gmail.com> > --- > .../devicetree/bindings/nvdimm/nvdimm-region.txt | 45 ++++++++++++++++++++++ > 1 file changed, 45 insertions(+) > create mode 100644 Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt > > diff --git a/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt > new file mode 100644 > index 000000000000..02091117ff16 > --- /dev/null > +++ b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt > @@ -0,0 +1,45 @@ > +Device-tree bindings for NVDIMM memory regions > +----------------------------------------------------- > + > +Non-volatile DIMMs are memory modules used to provide (cacheable) main memory Are DIMMs always going to be the only form factor for NV memory? And if you have multiple DIMMs, does each DT node correspond to a DIMM? If not, then what if we want/need to provide power control to a DIMM? > +that retains its contents across power cycles. In more practical terms, they > +are kind of storage device where the contents can be accessed by the CPU > +directly, rather than indirectly via a storage controller or similar. The an > +nvdimm-region specifies a physical address range that is hosted on an NVDIMM > +device. > + > +Bindings for the region nodes: > +----------------------------- > + > +Required properties: > + - compatible = "nvdimm-region" > + > + - reg = <base, size>; > + The system physical address range of this nvdimm region. > + > +Optional properties: > + - Any relevant NUMA assocativity properties for the target platform. > + - A "volatile" property indicating that this region is actually in > + normal DRAM and does not require cache flushes after each write. > + > +A complete example: > +-------------------- > + > +/ { > + #size-cells = <2>; > + #address-cells = <2>; > + > + platform { Perhaps we need a more well defined node here. Like we have 'memory' for memory nodes. > + region@5000 { > + compatible = "nvdimm-region; > + reg = <0x00000001 0x00000000 0x00000000 0x40000000> > + > + }; > + > + region@6000 { > + compatible = "nvdimm-region"; > + reg = <0x00000001 0x00000000 0x00000000 0x40000000> Your reg property and unit-address don't match and you have overlapping regions. > + volatile; > + }; > + }; > +}; > -- > 2.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Mar 27, 2018 at 9:24 AM, Rob Herring <robh@kernel.org> wrote: > On Fri, Mar 23, 2018 at 07:12:09PM +1100, Oliver O'Halloran wrote: >> Add device-tree binding documentation for the nvdimm region driver. >> >> Cc: devicetree@vger.kernel.org >> Signed-off-by: Oliver O'Halloran <oohall@gmail.com> >> --- >> .../devicetree/bindings/nvdimm/nvdimm-region.txt | 45 ++++++++++++++++++++++ >> 1 file changed, 45 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >> >> diff --git a/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >> new file mode 100644 >> index 000000000000..02091117ff16 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >> @@ -0,0 +1,45 @@ >> +Device-tree bindings for NVDIMM memory regions >> +----------------------------------------------------- >> + >> +Non-volatile DIMMs are memory modules used to provide (cacheable) main memory > > Are DIMMs always going to be the only form factor for NV memory? > > And if you have multiple DIMMs, does each DT node correspond to a DIMM? A nvdimm-region might correspond to a single NVDIMM, a set of interleaved NVDIMMs, or it might just be a chunk of normal memory that you want treated as a NVDIMM for some reason. The last case is useful for provisioning install media on servers since it allows you do download a DVD image, turn it into an nvdimm-region, and kexec into the installer which can use it as a root disk. That may seem a little esoteric, but it's handy and we're using a full linux environment for our boot loader so it's easy to make use of. > If not, then what if we want/need to provide power control to a DIMM? That would require a DIMM (and probably memory controller) specific driver. I've deliberately left out how regions are mapped back to DIMMs from the binding since it's not really clear to me how that should work. A phandle array pointing to each DIMM device (which could be anything) would do the trick, but I've found that a bit awkward to plumb into the model that libnvdimm expects. >> +that retains its contents across power cycles. In more practical terms, they >> +are kind of storage device where the contents can be accessed by the CPU >> +directly, rather than indirectly via a storage controller or similar. The an >> +nvdimm-region specifies a physical address range that is hosted on an NVDIMM >> +device. >> + >> +Bindings for the region nodes: >> +----------------------------- >> + >> +Required properties: >> + - compatible = "nvdimm-region" >> + >> + - reg = <base, size>; >> + The system physical address range of this nvdimm region. >> + >> +Optional properties: >> + - Any relevant NUMA assocativity properties for the target platform. >> + - A "volatile" property indicating that this region is actually in >> + normal DRAM and does not require cache flushes after each write. >> + >> +A complete example: >> +-------------------- >> + >> +/ { >> + #size-cells = <2>; >> + #address-cells = <2>; >> + >> + platform { > > Perhaps we need a more well defined node here. Like we have 'memory' for > memory nodes. I think treating it as a platform device is fine. Memory nodes are special since the OS needs to know where it can allocate early in boot and I don't see non-volatile memory as being similarly significant. Fundamentally an NVDIMM is just a memory mapped storage device so we should be able to defer looking at them until later in boot. That said you might have problems with XIP kernels and what not. I think that problem is better solved through other means though. >> + region@5000 { >> + compatible = "nvdimm-region; >> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> >> + >> + }; >> + >> + region@6000 { >> + compatible = "nvdimm-region"; >> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> > > Your reg property and unit-address don't match and you have overlapping > regions. Yep, those are completely screwed up. >> + volatile; >> + }; >> + }; >> +}; >> -- >> 2.9.5 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe devicetree" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Mar 27, 2018 at 9:53 AM, Oliver <oohall@gmail.com> wrote: > On Tue, Mar 27, 2018 at 9:24 AM, Rob Herring <robh@kernel.org> wrote: >> On Fri, Mar 23, 2018 at 07:12:09PM +1100, Oliver O'Halloran wrote: >>> Add device-tree binding documentation for the nvdimm region driver. >>> >>> Cc: devicetree@vger.kernel.org >>> Signed-off-by: Oliver O'Halloran <oohall@gmail.com> >>> --- >>> .../devicetree/bindings/nvdimm/nvdimm-region.txt | 45 ++++++++++++++++++++++ >>> 1 file changed, 45 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>> >>> diff --git a/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>> new file mode 100644 >>> index 000000000000..02091117ff16 >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>> @@ -0,0 +1,45 @@ >>> +Device-tree bindings for NVDIMM memory regions >>> +----------------------------------------------------- >>> + >>> +Non-volatile DIMMs are memory modules used to provide (cacheable) main memory >> >> Are DIMMs always going to be the only form factor for NV memory? >> >> And if you have multiple DIMMs, does each DT node correspond to a DIMM? > > A nvdimm-region might correspond to a single NVDIMM, a set of > interleaved NVDIMMs, or it might just be a chunk of normal memory that > you want treated as a NVDIMM for some reason. The last case is useful > for provisioning install media on servers since it allows you do > download a DVD image, turn it into an nvdimm-region, and kexec into > the installer which can use it as a root disk. That may seem a little > esoteric, but it's handy and we're using a full linux environment for > our boot loader so it's easy to make use of. I'm really just asking if we should drop the "dimm" name because it is not always a DIMM. Maybe pmem instead? I don't know, naming is hard(TM). >> If not, then what if we want/need to provide power control to a DIMM? > > That would require a DIMM (and probably memory controller) specific > driver. I've deliberately left out how regions are mapped back to > DIMMs from the binding since it's not really clear to me how that > should work. A phandle array pointing to each DIMM device (which could > be anything) would do the trick, but I've found that a bit awkward to > plumb into the model that libnvdimm expects. > >>> +that retains its contents across power cycles. In more practical terms, they >>> +are kind of storage device where the contents can be accessed by the CPU >>> +directly, rather than indirectly via a storage controller or similar. The an >>> +nvdimm-region specifies a physical address range that is hosted on an NVDIMM >>> +device. >>> + >>> +Bindings for the region nodes: >>> +----------------------------- >>> + >>> +Required properties: >>> + - compatible = "nvdimm-region" >>> + >>> + - reg = <base, size>; >>> + The system physical address range of this nvdimm region. >>> + >>> +Optional properties: >>> + - Any relevant NUMA assocativity properties for the target platform. >>> + - A "volatile" property indicating that this region is actually in >>> + normal DRAM and does not require cache flushes after each write. >>> + >>> +A complete example: >>> +-------------------- >>> + >>> +/ { >>> + #size-cells = <2>; >>> + #address-cells = <2>; >>> + >>> + platform { >> >> Perhaps we need a more well defined node here. Like we have 'memory' for >> memory nodes. > > I think treating it as a platform device is fine. Memory nodes are Platform device is a Linux term... > special since the OS needs to know where it can allocate early in boot > and I don't see non-volatile memory as being similarly significant. > Fundamentally an NVDIMM is just a memory mapped storage device so we > should be able to defer looking at them until later in boot. It's not clear if 'platform' is just an example or random name or what the node is required to be called. In the latter case, we should be much more specific because 'platform' could be anything. In the former case, then we have no way to find or validate the node because the name could be anything and there's no compatible property either. "region" is pretty generic too. > > That said you might have problems with XIP kernels and what not. I > think that problem is better solved through other means though. > >>> + region@5000 { >>> + compatible = "nvdimm-region; >>> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> >>> + >>> + }; >>> + >>> + region@6000 { >>> + compatible = "nvdimm-region"; >>> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> Thinking about this some more, the 2 levels of nodes is pointless. Just follow memory nodes structure. nv-memory@100000000 { compatible = "nvdimm-region"; reg = <0x00000001 0x00000000 0x00000000 0x40000000>; }; nv-memory@200000000 { compatible = "nvdimm-region"; reg = <0x00000002 0x00000000 0x00000000 0x40000000>; }; or: nv-memory@100000000 { compatible = "nvdimm-region"; reg = <0x00000001 0x00000000 0x00000000 0x40000000> <0x00000002 0x00000000 0x00000000 0x40000000>; }; Both forms should be allowed. Rob
On Wed, Mar 28, 2018 at 10:06 AM, Rob Herring <robh@kernel.org> wrote: [..] > >> Are DIMMs always going to be the only form factor for NV memory? > >> > >> And if you have multiple DIMMs, does each DT node correspond to a DIMM? > > > > A nvdimm-region might correspond to a single NVDIMM, a set of > > interleaved NVDIMMs, or it might just be a chunk of normal memory that > > you want treated as a NVDIMM for some reason. The last case is useful > > for provisioning install media on servers since it allows you do > > download a DVD image, turn it into an nvdimm-region, and kexec into > > the installer which can use it as a root disk. That may seem a little > > esoteric, but it's handy and we're using a full linux environment for > > our boot loader so it's easy to make use of. > > I'm really just asking if we should drop the "dimm" name because it is > not always a DIMM. Maybe pmem instead? I don't know, naming is > hard(TM). The Linux enabling uses the term "memory device". The Linux device object name for memory devices is "nmem". [..] > > special since the OS needs to know where it can allocate early in boot > > and I don't see non-volatile memory as being similarly significant. > > Fundamentally an NVDIMM is just a memory mapped storage device so we > > should be able to defer looking at them until later in boot. > > It's not clear if 'platform' is just an example or random name or what > the node is required to be called. In the latter case, we should be > much more specific because 'platform' could be anything. In the former > case, then we have no way to find or validate the node because the > name could be anything and there's no compatible property either. > > "region" is pretty generic too. > The term "nvdimm-region" has specific meaning to the libnvdimm sub-system. It is a contiguous physical address range backed by one or more memory devices, DIMMs, in an interleaved configuration (interleave set). One feature that is currently missing from libnvdimm is a management interface to change an interleave configuration. To date, Linux only reads a static region configuration published by platform firmware. Linux can provide dynamic provisioning of namespaces out of those regions, but interleave configuration has been left to vendor specific tooling to date. It would be great to start incorporating generic Linux support for that capability across platform firmware implementations.
On Thu, Mar 29, 2018 at 4:06 AM, Rob Herring <robh@kernel.org> wrote: > On Tue, Mar 27, 2018 at 9:53 AM, Oliver <oohall@gmail.com> wrote: >> On Tue, Mar 27, 2018 at 9:24 AM, Rob Herring <robh@kernel.org> wrote: >>> On Fri, Mar 23, 2018 at 07:12:09PM +1100, Oliver O'Halloran wrote: >>>> Add device-tree binding documentation for the nvdimm region driver. >>>> >>>> Cc: devicetree@vger.kernel.org >>>> Signed-off-by: Oliver O'Halloran <oohall@gmail.com> >>>> --- >>>> .../devicetree/bindings/nvdimm/nvdimm-region.txt | 45 ++++++++++++++++++++++ >>>> 1 file changed, 45 insertions(+) >>>> create mode 100644 Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>>> >>>> diff --git a/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>>> new file mode 100644 >>>> index 000000000000..02091117ff16 >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt >>>> @@ -0,0 +1,45 @@ >>>> +Device-tree bindings for NVDIMM memory regions >>>> +----------------------------------------------------- >>>> + >>>> +Non-volatile DIMMs are memory modules used to provide (cacheable) main memory >>> >>> Are DIMMs always going to be the only form factor for NV memory? >>> >>> And if you have multiple DIMMs, does each DT node correspond to a DIMM? >> >> A nvdimm-region might correspond to a single NVDIMM, a set of >> interleaved NVDIMMs, or it might just be a chunk of normal memory that >> you want treated as a NVDIMM for some reason. The last case is useful >> for provisioning install media on servers since it allows you do >> download a DVD image, turn it into an nvdimm-region, and kexec into >> the installer which can use it as a root disk. That may seem a little >> esoteric, but it's handy and we're using a full linux environment for >> our boot loader so it's easy to make use of. > > I'm really just asking if we should drop the "dimm" name because it is > not always a DIMM. Maybe pmem instead? I don't know, naming is > hard(TM). pmem is probably a better name. I'll fix that up. >>> If not, then what if we want/need to provide power control to a DIMM? >> >> That would require a DIMM (and probably memory controller) specific >> driver. I've deliberately left out how regions are mapped back to >> DIMMs from the binding since it's not really clear to me how that >> should work. A phandle array pointing to each DIMM device (which could >> be anything) would do the trick, but I've found that a bit awkward to >> plumb into the model that libnvdimm expects. >> >>>> +that retains its contents across power cycles. In more practical terms, they >>>> +are kind of storage device where the contents can be accessed by the CPU >>>> +directly, rather than indirectly via a storage controller or similar. The an >>>> +nvdimm-region specifies a physical address range that is hosted on an NVDIMM >>>> +device. >>>> + >>>> +Bindings for the region nodes: >>>> +----------------------------- >>>> + >>>> +Required properties: >>>> + - compatible = "nvdimm-region" >>>> + >>>> + - reg = <base, size>; >>>> + The system physical address range of this nvdimm region. >>>> + >>>> +Optional properties: >>>> + - Any relevant NUMA assocativity properties for the target platform. >>>> + - A "volatile" property indicating that this region is actually in >>>> + normal DRAM and does not require cache flushes after each write. >>>> + >>>> +A complete example: >>>> +-------------------- >>>> + >>>> +/ { >>>> + #size-cells = <2>; >>>> + #address-cells = <2>; >>>> + >>>> + platform { >>> >>> Perhaps we need a more well defined node here. Like we have 'memory' for >>> memory nodes. >> >> I think treating it as a platform device is fine. Memory nodes are > > Platform device is a Linux term... > >> special since the OS needs to know where it can allocate early in boot >> and I don't see non-volatile memory as being similarly significant. >> Fundamentally an NVDIMM is just a memory mapped storage device so we >> should be able to defer looking at them until later in boot. > > It's not clear if 'platform' is just an example or random name or what > the node is required to be called. In the latter case, we should be > much more specific because 'platform' could be anything. In the former > case, then we have no way to find or validate the node because the > name could be anything and there's no compatible property either. Sorry, the platform node is just there as an example. I'll remove it. > "region" is pretty generic too. It is, but I didn't see a compelling reason to call it something else. >> That said you might have problems with XIP kernels and what not. I >> think that problem is better solved through other means though. >> >>>> + region@5000 { >>>> + compatible = "nvdimm-region; >>>> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> >>>> + >>>> + }; >>>> + >>>> + region@6000 { >>>> + compatible = "nvdimm-region"; >>>> + reg = <0x00000001 0x00000000 0x00000000 0x40000000> > > Thinking about this some more, the 2 levels of nodes is pointless. > Just follow memory nodes structure. > > nv-memory@100000000 { > compatible = "nvdimm-region"; > reg = <0x00000001 0x00000000 0x00000000 0x40000000>; > }; > > nv-memory@200000000 { > compatible = "nvdimm-region"; > reg = <0x00000002 0x00000000 0x00000000 0x40000000>; > }; > > or: > > nv-memory@100000000 { > compatible = "nvdimm-region"; > reg = <0x00000001 0x00000000 0x00000000 0x40000000> > <0x00000002 0x00000000 0x00000000 0x40000000>; > }; > > Both forms should be allowed. In the example you need two separate nodes since one has the "volatile" property to indicate it's backed by normal memory while the other doesn't. That detail is important since the OS can skip doing cache flushes when writing to a region that it knows is volatile. Anyway, the usefulness of having multiple ranges in the reg is a bit dubious since you should never see dis-contiguous ranges of memory backed by the same devices. Keep in mind that this binding here is deliberately skeletal and leaves out the parts required to map the region to the backing devices, once that is added there's not going to be a whole lot of room for coalescing nodes. That said, I'll add support for it anyway since it might be nice to have for hand-written DTs (ours are mostly generated by FW). Thanks, Oliver
diff --git a/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt new file mode 100644 index 000000000000..02091117ff16 --- /dev/null +++ b/Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt @@ -0,0 +1,45 @@ +Device-tree bindings for NVDIMM memory regions +----------------------------------------------------- + +Non-volatile DIMMs are memory modules used to provide (cacheable) main memory +that retains its contents across power cycles. In more practical terms, they +are kind of storage device where the contents can be accessed by the CPU +directly, rather than indirectly via a storage controller or similar. The an +nvdimm-region specifies a physical address range that is hosted on an NVDIMM +device. + +Bindings for the region nodes: +----------------------------- + +Required properties: + - compatible = "nvdimm-region" + + - reg = <base, size>; + The system physical address range of this nvdimm region. + +Optional properties: + - Any relevant NUMA assocativity properties for the target platform. + - A "volatile" property indicating that this region is actually in + normal DRAM and does not require cache flushes after each write. + +A complete example: +-------------------- + +/ { + #size-cells = <2>; + #address-cells = <2>; + + platform { + region@5000 { + compatible = "nvdimm-region; + reg = <0x00000001 0x00000000 0x00000000 0x40000000> + + }; + + region@6000 { + compatible = "nvdimm-region"; + reg = <0x00000001 0x00000000 0x00000000 0x40000000> + volatile; + }; + }; +};
Add device-tree binding documentation for the nvdimm region driver. Cc: devicetree@vger.kernel.org Signed-off-by: Oliver O'Halloran <oohall@gmail.com> --- .../devicetree/bindings/nvdimm/nvdimm-region.txt | 45 ++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvdimm/nvdimm-region.txt