Re: 回信： [openrisc] saving/restoring context at exceptions

["Damjan Lampret" <lampret@opencores.org>]

----- Original Message -----
From: <jimmy87@sunplus.com.tw>
To: <openrisc@opencores.org>
Sent: Monday, June 12, 2000 2:36 AM
Subject: 回信： [openrisc] saving/restoring context at exceptions


>
>
> Hi Damjan,
> I think we also need to save FLAG register.
> We need to restore the flag bit if the exception happens in the branch
insn

Sure. But CCR can be saved just like GPRs by exception handler itself.

> or in the branch delay slot insn. I think EXR could be tossed away since
> CPU already enters exception service routine.

Yeah, but what happens if you want to nest exceptions (nested interrupts for
example or higher priority exceptions interrupting lower priority exceptions
etc.). IMO EXR and SUPV should be saved/restored.

regards,
Damjan