[Linaro-open-discussions] Notes on Linaro Open Discussions meeting 4 Nov 2020

Lorenzo Pieralisi lorenzo.pieralisi at arm.com
Fri Nov 6 14:36:15 UTC 2020


On Thu, Nov 05, 2020 at 12:36:21PM +0000, Jonathan Cameron via Linaro-open-discussions wrote:

[...]

> IORT - Reserve memory regions (RMR)
> ===================================
> 
> * Shameer gave summary
>  - IORT Revision E (https://developer.arm.com/documentation/den0049/latest/) introduced new node type.
>  - A way to describe memory regions that should have unity mapping in the SMMU.
>  - Use case is a PCIe RAID card that has FW that uses a pool of host memory (hidden from OS).
> 
> * Status
>  - Patches out for ACPICA
>    - Question raised by ACPICA reviewers on whether spec is final
>    - Spec appears final  (Lorenzo to check) but may be minor unrelated fix in doc to come (Sami).
>  - Patches out for kernel on relevant lists.
>    - Mail from Steven Price (Arm) - (Sami Mujawar who was on the call also involved) interested for EFI
>      framebuffer use case.
> 
> * Open questions
>  - Equivalent from AMD has flag to indicate that unity mapping only needed until driver has taken over
>    (end of kernel boot assumed).  Avoids and issue of holes in address space for VMs.
>    - Huawei not raising this as a requirement, but Lorenzo observed interesting and deserves discussion.

May I ask a pointer pls to relevant AMD docs and patches (if there are any) ?

Thanks,
Lorenzo


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