On 29-01-26, 07:29, Bertrand Marquis wrote:
Just a general question on the subject: Do we want to unmap the area from user space or should we never map it ?
I think maybe both, depending on the use case. But Google folks can confirm that the best as they understand the use cases well.
I am mentioning this because side effects could create issues if something is mapped in user space application but in fact not accessible or removed (barriers required, be careful with possible side effects of speculation, cache flush required etc...). Might be a better solution if the application is just getting an address but can never access it ?
The dma-buf API does provide some helpers to manage all that, I haven't used them yet but there is support to manage all this I think.
Yes having a dedicated heap for that sounds like a better solution as passing the information through and handling the unmapping would require a new concept. But as Achin said maybe that is not a need just for our use case but more general in the future so we might want to investigate a generic lend solution.
Yeah, maybe a generic LEND support is what we need.