Blue Swirl wrote: [snip] > > >> I would think this feature will be limited to platforms which can handle > > >> 32bit and 64bit binaries with a single personality. > > > > > > I am not sure it is a common case ! > > > > > > However, I suggest to emulate a 32 bit user linux system with a 64 bit > > > guest CPU running in 32 bit compatibily mode. It would be useful to test > > > 64 > > > bit CPUs in 32 bit compatibility mode. The only required modification in > > > linux user is to rename target_ulong so that it can have a different size > > > of the CPU word default size. > > > > Doesn't work for MIPS64, since it doesn't quite have a compatibility mode > > in the traditional sense. It needs to retain 64bit register width when > > running N32 ABI binaries. (Thus the somewhat odd overrides I added for > > the preliminary N32 support.) > > CPU registers (and storage for full width registers) would still be 64 > bits. The ABI uses of target_ulong need to be changed to, for example > abi_ulong so that the size can be changed.
I see. > Sparc64 does not have a compatibility mode either (except for address > masking), it can run Sparc32 binaries because of the cleverly designed > instruction set. Ops use full 64 bits of a register, but there are two > sets of CPU flags, 32 and 64 bits. For MIPS it's not even that much, sign-extension magic handles everything. Thiemo
