On 10/25/21 2:24 AM, LIU Zhiwei wrote:
I think extending on write is the correct thing.
Thanks. I will pick this way.
Jumps, exception entry and return, gdb write.
If we carefully process jumps and gdb write, I think we can omit exception entry and
return. Is it right?
No, though you'd probably have to create a special test case to see it.
On exception return, a 64-bit OS can write a 64-bit value into SEPC. But when SEPC is
copied to PC during SRET, UXL should be examined and the assignment should extend for a
32-bit user program.
Exception entry would seem to be limited on its face by SXLEN; STVEC will always contain
the same number of bits as PC, so no (additional) extension would be required. But we do
have to be careful to interpret the target_ulong value properly for the current SXLEN.
r~
