On 7/22/2021 12:26 PM, Jason Gunthorpe wrote:
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:
On Sat, Jul 17, 2021 at 02:21:32PM -0500, Alex Sierra wrote:
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?
The reason we used fake SPM approach was to have a "special memory"
not managed by Linux (NOT registered as normal system memory). But
also accessible by the CPU.
For device_generic we cannot allocate new physical addresses.
We need the physical address to match the actual system memory
physical address, so that CPU mappings work as expected.
Would you recommend to use a different approach?
Regards,
Alex Sierra
Jason
