On 8 July 2015 at 10:31, Andrew Chew <ac...@nvidia.com> wrote: > On Wed, Jul 08, 2015 at 10:18:36AM +1000, Ben Skeggs wrote: >> > There's some minimal state that needs to be mapped into GPU address space. >> > One thing that comes to mind are pushbuffers, which are needed to submit >> > stuff to any engine. >> I guess you can probably use the start of the kernel's address space >> carveout for these kind of mappings actually? It's not like userspace >> can ever have virtual addresses there? > > Yeah. I'm looking into it further, but to answer your original question, > I believe there is essentially an address range that nouveau would know > about, which it uses for fixed address allocations (I'm referring to how > the nvgpu driver does things...we may or may not come up with something > different for nouveau). > > Although it's dangerous, AFAIK the allocator in nouveau starts allocating > addresses at page 1, and as you suggested, one wouldn't ever get a CPU > address that low. But having a set of addresses reserved would be much > better of course. I'm thinking more about the top of the address space. As I understand it, the kernel already splits the CPU virtual address space into user/system areas (3GiB/1GiB for 32-bit IIUC), or something very similar to that.
Perhaps, if we can get at that information, we can use those same definitions for GPU address space? > _______________________________________________ > Nouveau mailing list > Nouveau@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/nouveau _______________________________________________ Nouveau mailing list Nouveau@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/nouveau
