Hi, On Thu, 3 Aug 2023 at 23:04, Pintu Agarwal <pintu.ping@xxxxxxxxx> wrote: > > Hi, > > On Wed, 2 Aug 2023 at 15:17, Christoph Hellwig <hch@xxxxxx> wrote: > > > > On Tue, Aug 01, 2023 at 10:39:04PM -0700, John Stultz wrote: > > > So, forgive me, I've not had a chance to look into this, but my > > > recollection was "reserved" is the name we see on x86, but other names > > > are possibly provided via the dts node? > > > No, I think "reserved" is the name hard-coded (for all arch) in Kernel > for global-cma. > So, I don't think this is x86 specific. I am checking on arm32 itself. > When we can dma_alloc_coherent we see these in the logs (if dts region > is not present). > cma: cma_alloc(cma (ptrval), name: reserved, count 64, align 6) > Now, with this change we will see this: > cma: cma_alloc(cma (ptrval), name: global-cma-region, count 64, align 6) > > > Indeed, dma_contiguous_default_area can also be set through > > rmem_cma_setup, which then takes the name from DT. > > > I think this is a different case. If DT entry is present we get this: > Reserved memory: created CMA memory pool at 0x98000000, name: name: > linux,cma, size 128 MiB > cma: cma_alloc(cma (ptrval), name: linux,cma, count 64, align 6) > > Here we are talking about the default hard-coded name in Kernel code > if DT is not defined. > So, in one of the boards, this DT entry was not present and it shows > as "reserved". > > > > I believe on the hikey board its "linux,cma" is the name, so forcing > > > it to reserved would break that. > > > > Yes, everywhere in the DT it's defined as "linux,cma". > You mean this also should be changed to "linux,cma-global-region" > everywhere with this change ? > > > > Maybe instead add a compat config option to force the cma name (so x86 > > > can set it to "default" if needed)? > > > Yes, having it in config is also a good option instead of hard-coding in Kernel. > > > > I think we'll just need to leave it as-is. I with dma-heaps had never > > exposed the name to userspace, but we'll have to lіve with it now. > > Can you point me to the userspace utility we are talking about here ? > I think we should not worry much about userspace name exposure. > I guess it should fetch whatever is declared in Kernel or DTS, right ? Just to follow-up on this. For now, can we change the Kernel hard-coded value from "reserved" to "global-cma-region" ? Later, for the DTS defined name let it be "linux,cma" or change that also to "linux,global-cma-region" ? Will this make sense ?
