On Thu, Feb 18, 2010 at 4:41 PM, Dmitry Antipov <anti...@mvista.com> wrote: > Hello all, > > is there any support for 64-bit MMIO?
No, though there has been some discussion about it before which you can find in the archives. 64 bit MMIO would be useful for Sparc32, Sparc64 and Alpha. > I'm trying to emulate 16750-like UART by adopting current 16550A emulation. > The problem is that my (MIPS) hardware is 64-bit, and native software > issues 64-bit load/stores (LD/SD) to talk with all hardware registers, > which are all 64-bit too (for UART case, only 8 lower bits are used, BTW). > As I can see, qemu splits 64-bit access into two 32-bit back-to-back ones, > but this gives catastrophic results if host and guest has different > byte order - i.e. write 0x0000000000000001 to 0x100 gives write 0x00000000 > to 0x100 and 0x10000000 to 0x104 because 64-bit quantities are swapped > within > 32-bit halves. The numbers don't look correct. Anyway, I'd suspect the device should do some byte swapping. Without code it's hard to tell.
