Thiemo Seufer wrote: > Paul Brook wrote: >>>> I think what you mean is that they work the way that ppc64 is defined, to >>>> remain compatible with ppc32. IMHO this is entirely irrelevant as we're >>>> emulating a ppc32. You could replace the high bits with garbage and >>>> nothing would ever be able to tell the difference. >>> PowerPC is a 64 bits architecture. PowerPC 32 on 32 bits host is >>> optimized not to compute the 32 highest bits, the same way it's allowed >>> to cut down the GPR when implementing a CPU that would not support the >>> 64 bits mode (but this is a tolerance, this is not the architecture is >>> defined). >> No. PowerPC is defined as a 64-bit archirecure. However there is a subset of >> this architecture (aka ppc32) that is a complete 32-bit architecture in its >> own right. By your own admission, we can get away with not calculating the >> high 32 bit of the register. If follows that the high bits are completely >> meaningless. > > This btw. also means that the ppc32 emulation on 32-bit hosts is needlessly > inefficient if the high bits are carried around. > >> The qemu ppc32 emulation is implemented in such a way that on 64-bit hosts >> it >> looks a lot like a ppc64 implementation. However this need not, and should >> not be exposed to the user. >> >>> OK. Those are real bugs to be fixed. I'll take a look.... But I'll try >>> not to break the GPR dump. In fact, GPR should always dumped as 64 bits, >>> even when runnig on 32 bits hosts. This would be more consistent with >>> the specification. >> I disagree. qemu is implementing ppc32. Showing more than 32 bits of >> register >> is completely bogus. Any differences between a 32-bit host and a 64-bit host >> are a qemu bug. If you display 64 bits, then those 64 bits had better be the >> same when run on 32-bit hosts. > > I strongly agree with Paul.
I strongly agree too and I suggest to remove the type ppc_gpr_t and to replace it with target_ulong (and uint32_t for the high part of the SPE extensions). Regards, Fabrice.