> On 03/01/2013 09:58 PM, Paul Brook wrote:
> >> +#ifdef TARGET_WORDS_BIGENDIAN
> >> + if (arm_feature(env, ARM_FEATURE_V6)
> >> + || arm_feature(env, ARM_FEATURE_V7)) {
> >> + /* IE and EE bits stay set for big-endian */
> >> + env->cp15.c1_sys |= (1 << 31) | (1 << 25);
> >> + }
> >> +#endif
> >
> > This is wrong for all the CPUs QEMU crrently supports. SCTLR.IE is
> > defined to be zero.
>
> Again I'd like to have more information. Why is it wrong to set IE when
> we are in big-endian?
The ARM architecture defines two big-endian modes. In BE8 mode only data
accesses big-endian, code fetches are still little-endian. In BE32 mode both
code and data are big-endian. In theory a fourth mode (big-endian code,
little-endian data) exists, though I've never seen that used.
All the v7 cores QEMU currently supports[1] only implement BE8 mode. The IE
bit is reserved and most be zero. Usermode emulation implements both, but the
privileged cp15 registers can safely be ignored there.
Paul
[1] Except maybe the M profile cores, but they use a different system model
anyway.
