28 Jan
2026
28 Jan
'26
3:01 p.m.
On Wed, 28 Jan 2026 at 19:59, Arnd Bergmann arnd@linaro.org wrote:
If I understand you correctly, I think you need a dmabuf object that is mapped neither into the kernel nor into userspace, and to me that sounds like you should not be using the system heap for that, since that remains mapped into the kernel and is accessible from userspace as well.
That is doable with the help of a custom heap. Not an issue.
The dma_map_sgtable() call in turn does not have to know about LEND vs SHARE, as all it does is map the memory into a bus address that can be shared with the firmware.
The FFA memory share interface has a different interface for LEND, and so I need to distinguish LEND vs SHARE there as well in device specific dma-ops.
-- Viresh