On Tue, May 4, 2021 at 9:40 AM Niklas Schnelle <schnelle@xxxxxxxxxxxxx> wrote: > On Mon, 2021-05-03 at 18:07 +0200, Arnd Bergmann wrote: > > - for the risc-v patch, I would suggest explaining that this fixes > > an existing runtime bug, not just a compiler error: > > | This is already broken, as accessing a fixed I/O port number of > > | an ISA device on NOMMU RISC-V would turn into a NULL pointer > > | dereference. > > Feel free to either copy this, or use your own explanation. > > I mixed the above in with the current commit message: > > Without MMU support PCI_IOBASE is left undefined because PCI_IO_END is > VMEMMAP_START. Nevertheless the in*()/out*() helper macros are left > defined with uses of PCI_IOBASE. At the moment this only compiles > because asm-generic/io.h defines PCI_IOBASE as 0 if it is undefined and > so at macro expansion PCI_IOBASE is defined. This leads to compilation > errors when asm-generic/io.h is changed to leave PCI_IOBASE undefined. > More importantly it is currently broken at runtime, as accessing a fixed > I/O port number of an ISA device on NOMMU RISC-V would turn into a NULL > pointer dereference. Instead only define the in*()/out*() helper macros > with MMU support and fall back to the asm-generic/io.h helper stubs > otherwise. Looks good, thanks. Maybe split into two or three paragraphs for readability. Arnd