On Tue, 2015-03-10 at 20:34 +1100, Benjamin Herrenschmidt wrote: > On Tue, 2015-03-10 at 18:36 +1100, Michael Ellerman wrote: > > We currently have a "special" syscall for switching endianness. This is > > syscall number 0x1ebe, which is handled explicitly in the 64-bit syscall > > exception entry. > > > > That has a few problems, firstly the syscall number is outside of the > > usual range, which confuses various tools. For example strace doesn't > > recognise the syscalls at all. > > > > Secondly it's handled explicitly as a special case in the syscall > > exception entry, which is complicated enough without it. > > > > As a first step toward removing the special syscall, we need to add a > > regular syscall that implements the same functionality. > > > > The logic is simple, it simply toggles the MSR_LE bit in the userspace > > MSR. This is the same as the special syscall, with the caveat that the > > special syscall clobbers fewer registers. > > You can set _TIF_RESTOREALL to force a restore of all the registers on > the way back which should do the job.
Right, I'd forgotten we talked about that. I'll try that tomorrow. cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
