From: Justin Carlson <justin@cs.cmu.edu>
To: Justin Carlson <justin@cs.cmu.edu>
Cc: linux-mips@oss.sgi.com
Subject: Re: reenabling interrupts on return from function
Date: 15 Jun 2002 15:22:28 -0700 [thread overview]
Message-ID: <1024179748.1549.12.camel@localhost.localdomain> (raw)
In-Reply-To: <1024177741.1549.4.camel@localhost.localdomain>
On Sat, 2002-06-15 at 14:49, Justin Carlson wrote:
> I'm obviously missing something basic here.
>
> Looking at stackframe.h, I see this code as a part of RESTORE_SOME
>
>
> mfc0 t0, CP0_STATUS; \
> .set pop; \
> ori t0, 0x1f; \
> xori t0, 0x1f; \
> mtc0 t0, CP0_STATUS;
>
OK, this was a stupid question; the answer was staring me in the face
(the restoration of the status register from the stack), and I didn't
see it.
However, I still don't see the point of the above code. Why do we
explicitly clear bits 4-0 of the status register just before reloading
it from the system stack?
-Justin
next prev parent reply other threads:[~2002-06-15 22:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-06-15 21:49 reenabling interrupts on return from function Justin Carlson
2002-06-15 22:22 ` Justin Carlson [this message]
2002-06-19 15:16 ` Maciej W. Rozycki
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