diff options
Diffstat (limited to 'hwaccess.c')
-rw-r--r-- | hwaccess.c | 24 |
1 files changed, 20 insertions, 4 deletions
@@ -49,13 +49,29 @@ int io_fd; */ static inline void sync_primitive(void) { -/* This is needed only on PowerPC because... - * - x86 uses uncached accesses which have a strongly ordered memory model and - * - MIPS uses uncached accesses in mode 2 on /dev/mem which has also a strongly ordered memory model - * - ARM uses a strongly ordered memory model for device memories. +/* This is not needed for... + * - x86: uses uncached accesses which have a strongly ordered memory model. + * - MIPS: uses uncached accesses in mode 2 on /dev/mem which has also a strongly ordered memory model. + * - ARM: uses a strongly ordered memory model for device memories. + * + * See also https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/memory-barriers.txt */ #if IS_PPC // cf. http://lxr.free-electrons.com/source/arch/powerpc/include/asm/barrier.h asm("eieio" : : : "memory"); +#elif IS_SPARC +#if defined(__sparc_v9__) || defined(__sparcv9) + /* Sparc V9 CPUs support three different memory orderings that range from x86-like TSO to PowerPC-like + * RMO. The modes can be switched at runtime thus to make sure we maintain the right order of access we + * use the strongest hardware memory barriers that exist on Sparc V9. */ + asm volatile ("membar #Sync" ::: "memory"); +#elif defined(__sparc_v8__) || defined(__sparcv8) + /* On SPARC V8 there is no RMO just PSO and that does not apply to I/O accesses... but if V8 code is run + * on V9 CPUs it might apply... or not... we issue a write barrier anyway. That's the most suitable + * operation in the V8 instruction set anyway. If you know better then please tell us. */ + asm volatile ("stbar"); +#else + #error Unknown and/or unsupported SPARC instruction set version detected. +#endif #endif } |