[PATCH v3 0/8] Support DEVICE_GENERIC memory in migrate_vma_*

[Theodore Y. Ts'o]

On Wed, Jun 23, 2021 at 05:49:55PM -0400, Felix Kuehling wrote:
> 
> I can think of two ways to test the changes for MEMORY_DEVICE_GENERIC in
> this patch series in a way that is reproducible without special hardware and
> firmware:
> 
> For the reference counting changes we could use the dax driver with hmem and
> use efi_fake_mem on the kernel command line to create some DEVICE_GENERIC
> pages. I'm open to suggestions for good user mode tests to exercise dax
> functionality on this type of memory.

Sorry for the thread necromancy, but now that the merge window is
past....

Today I test ext4's dax support, without having any $$$ DAX hardware,
by using the kernel command line "memmap=4G!9G:memmap=9G!14G" which
reserves memory so that creates two pmem device and then I run
xfstests with DAX enabled using qemu or using a Google Compute Engine
VM, using TEST_DEV=/dev/pmem0 and SCRATCH_DEV=/dev/pmem1.

If you can give me a recipe for what kernel configs I should enable,
and what magic kernel command line arguments to use, then I'd be able
to test your patch set with ext4.

Cheers,

						- Ted