On Thu, Jul 30, 2020 at 09:58:21AM +0100, Peter Maydell wrote: > On Thu, 30 Jul 2020 at 08:42, Stefano Garzarella <sgarz...@redhat.com> wrote: > > I agree that it is better to return the dma_memory_rw() return value, but > > at first look, no one seems to check the return value of pci_dma_rw(), > > pci_dma_read(), andpci_dma_write(). > > > > Should we make them void? > > In general code (eg device models) that issues memory transactions > need to have a mechanism for finding out whether the transaction > succeeds. Traditionally QEMU didn't have the concept of a > transaction failing, but we have added it, starting with the > APIs at the bottom level (the address_space_* ones). We haven't > always plumbed the error-handling (or the memory-transaction > input, for that matter) through to some of these other APIs. > I think for consistency we should do that, and ideally we > should make all these APIs look the same as the base-level > address_space* ones, which would mean returning a MemTxError > rather than a bool.
Yeah, that makes a lot of sense to me. > > We should also figure out why the dma_* functions exist at all: > they include some calls to dma_barrier(), but not all devices > do DMA with the dma_* functions, so we have an inconsistency > that should be sorted out... > I've never looked in detail, but I agree we should have more consistency. Thanks for the details! Stefano
