Re: [Linux-nvdimm] [PATCH v2] pmem: Initial version of persistent memory driver

[Boaz Harrosh <boaz@plexistor.com>]

On 09/10/2014 08:03 PM, Dan Williams wrote:
> Hi Boaz,
> 
<>
>> We please need to start somewhere, no?
> 
> Sure, but you used the operative term "start", as in you already
> expect to enhance this capability down the road, right?
> 

Yes

> It's fine to dismiss this request_firmware() based approach, but don't
> mis-characterize it in the process.  With regards to describing device
> boundaries, a bus-descriptor-blob handed to the kernel is a superset
> of the capability provided by the kernel command line.  It can be
> injected statically at compile time, or dynamically loaded from the
> initrd or the rootfs.  It has the added benefit of being flexible to
> change whereas the kernel command line is a more permanent contract
> that we will need to maintain compatibility with in perpetuity.
> 

initrd or rootfs means for me "make install". But I want my fedora
to never make or install. Pre-compiled binary blobs including rootfs and
it needs to work.

> If you already see this bus description as a "starting" point, then I
> think we need an interface that is more amenable to ongoing change,
> that's not the kernel-command-line.
> 

module-command-line. a module can be loaded via udev and/or module param
can be changed dynamically on the fly. And also be specified via
kernel-command-line. So it is much less permanent contract API than
"rootfs"

And yes, I intend to add more interfaces. And No! I do not intend to
ever extend this module-param interface, that I can see. This one is
that, which it is right now. Later a sysfs/ objects will enable dynamic
management of devices. So both: initial device list on load - more devices
or removal on the fly, unload all on unload. This is my plan. So right
now I do not see this map= need ever change in the future. Only more
interfaces added in (the very near) future.

Thanks
Boaz