On 03/26/2015 10:32 AM, Christoph Hellwig wrote:
> Here is another version of the same trivial pmem driver, because two
> obviously aren't enough. The first patch is the same pmem driver
> that Ross posted a short time ago, just modified to use platform_devices
> to find the persistant memory region instead of hardconding it in the
> Kconfig. This allows to keep pmem.c separate from any discovery mechanism,
> but still allow auto-discovery.
>
Hi Christoph
So I've been trying to test your version, and play around with it.
I currently have some problems, but this is the end of the week for me
so I will debug and fix it after the weekend on Sunday.
But just a heads up for what I stumbled on.
For one this auto discovery of yours is very (very) nice but is a bit
inconvenience. Before I would reserve a big chuck on each NUMA range
on Kernel's memmap= And then at pmem map= would slice and dice it
as I want hot style on modprobe with no need for reboot. Now I need
to do it on reboot theoretically. (You know xfstest needs lots of devices
some big some small ;-))
theoretically because if I try:
memmap=1G!4G,1G!6G
It will not boot at all. (will debug on Sunday) I must have 2 devices
because each one is on another NUMA node.
If I do memmap=2G!4G,1G!6G , which is a contiguous range it will give
me only one device. Just an inconvenience. (And also this one sometimes
does not boot)
{All this in a VM for now did not even get to real HW yet}
Also with the modprob pmem map= I was supporting a PCIE memory card but
I guess I need to throw this one out the door.
Am also posting an RFC cleanup to your pmem driver. RFC because I was not
yet able to boot the all thing in our lab for heavy testing.
Thanks
Boaz
> The other two patches are a heavily rewritten version of the code that
> Intel gave to various storage vendors to discover the type 12 (and earlier
> type 6) nvdimms, which I massaged into a form that is hopefully suitable
> for mainline.
>
> Note that pmem.c really is the minimal version as I think we need something
> included ASAP. We'll eventually need to be able to do other I/O from and
> to it, and as most people know everyone has their own preferre method to
> do it, which I'd like to discuss once we have the basic driver in.
>
> This has been tested both with a real NVDIMM on a system with a type 12
> capable bios, as well as with "fake persistent" memory using the memmap=
> option.
>
> Changes since V1:
> - s/E820_PROTECTED_KERN/E820_PMEM/g
> - map the persistent memory as uncached
> - better kernel parameter description
> - various typo fixes
> - MODULE_LICENSE fix
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
