Date: Fri, 17 Sep 1999 09:33:57 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Mohit Aron <aron@cs.rice.edu> Cc: freebsd-hackers@freebsd.org Subject: Re: TLB miss handler for alpha running FreeBSD-4.0 Message-ID: <Pine.BSF.4.10.9909170930470.440-100000@salmon.nlsystems.com> In-Reply-To: <199909170410.XAA11255@cs.rice.edu>
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On Thu, 16 Sep 1999, Mohit Aron wrote: > Hi, > as I understand it, TLB misses on the alpha are handled by the > software (as opposed to x86 where they are handled in hardware). Can someone > help me with the FreeBSD code. I'm trying to locate the kernel code that > implements the TLB handler. I'd appreciate if someone can tell me how the > control is given to the software (i.e. what trap is generated), how the > handler is called and finally how does the control return back. Thanks, TLB misses are handled by the PALcode on the alpha (which is often part of the firmware). There is no trap handler in the FreeBSD code which needs to handle TLB misses as the PALcode deals with it transparently. PALcode is 'special' software which runs at a higher privilege level than the kernel and handles low-level traps, interrupts, etc., translating them into a standard form for the kernel's consumption. If a later processor revision needs different handling for low-level issues, it will use a different PALcode but will generally present the same interface to the kernel. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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