Re: [PATCH v4 10/13] lib: test_hmm add module param for zone device type

On Thu, Jul 22, 2021 at 11:59:17AM -0500, Sierra Guiza, Alejandro (Alex) wrote:

On 7/22/2021 7:23 AM, Jason Gunthorpe wrote:

quoted

On Sat, Jul 17, 2021 at 02:21:32PM -0500, Alex Sierra wrote:

quoted

In order to configure device generic in test_hmm, two
module parameters should be passed, which correspon to the
SP start address of each device (2) spm_addr_dev0 &
spm_addr_dev1. If no parameters are passed, private device
type is configured.

I don't think tests should need configuration like this, is it really
necessary? How can people with normal HW run this test?

Hi Jason,
The idea was to add an easy way to validate the codepaths touched by this
patch series, which make modifications to the migration helpers for device
generic type pages. We're using CONFIG_EFI_FAKE_MEMMAP to create fake SPM
devices inside system memory. No special HW needed. And passing the kernel
parameter efi_fake_mem. Ex. efi_fake_mem=1G@0x100000000:0x40000. I should
probably need to include a small example of how to set this in the
test_hmm.sh
usage().

I don't think anything about hmm is sensitive to how the pages are
acquired - you can't create device generic pages without relying on
FAKE_MEMMAP?

Jason