On Fri, Nov 23, 2018 at 11:01:55AM +0000, Russell King - ARM Linux wrote: > Yuck. So, if we have a 4GB non-PAE 32-bit system, or a PAE system > where we have valid memory across the 4GB boundary and no IOMMU, > we have to reserve the top 4K page in the first 4GB of RAM? But that is only needed when dma_addr_t is 32bit anyway, no? > Rather than inventing magic cookies like this, I'd much rather we > sanitised the API so that we have functions that return success or > an error code, rather than trying to shoe-horn some kind of magic > error codes into dma_addr_t and subtly break systems in the process. Sure, but is has the obvious downside that we need to touch every driver that uses these functions, and that are probably a lot of drivers. Regards, Joerg
