On 2020-09-15 16:51, Christoph Hellwig wrote: [...]
+These APIs allow to allocate pages in the kernel direct mapping that are +guaranteed to be DMA addressable. This means that unlike dma_alloc_coherent, +virt_to_page can be called on the resulting address, and the resulting
Nit: if we explicitly describe this as if it's a guarantee that can be relied upon...
+struct page can be used for everything a struct page is suitable for.
[...]
+This routine allocates a region of <size> bytes of consistent memory. It +returns a pointer to the allocated region (in the processor's virtual address +space) or NULL if the allocation failed. The returned memory may or may not +be in the kernels direct mapping. Drivers must not call virt_to_page on +the returned memory region.
...then forbid this document's target audience from relying on it, something seems off. At the very least it's unhelpfully unclear :/
Given patch #17, I suspect that the first paragraph is the one that's no longer true.
Robin.
