Re: port-mips/16154

"Toru Nishimura" <[email protected]> Sun, 24 Nov 2002 18:28:34 +0900
Newsgroups gmane.os.netbsd.ports.mips
Message-ID <000701c2939b$dd037340$0d00a8c0@paq5>
Stephen Ma <[email protected]> said;

> Toru> So, setting SR with the value there makes two bad things; to set
> Toru> EXL condition and start FPU mistakenly.  These bits must be
> Toru> turned off before MTC instruction updates SR.
>
> The patch only uses the IM mask bits from the SR value saved in the
> exception frame. The rest of the COP0 SR bits are preserved.

Sorry, it's my misunderstanding.

Chuck Silvers <[email protected]> said;

> one thing to be careful of here:  you must not allow nested interrupts
> of the same level as the one you're currently processing as long as the
> interrupt handler is using any stack space.  

I would like to make a similar change there.  Preserved IE, but IM cleared.
In R3000 case, copy IEp to IEc.  R4000 case, leave IE as it was.  Munch
outstanding interrupt conditions and re-enabling distinct IM bits (if
necessary) will be cpu_intr()'s responsibility.

Toru Nishimura/ALKYL Technology