From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailserv2.iuinc.com (qmailr@mailserv2.iuinc.com [206.245.164.55]) by sod.res.cmu.edu (8.8.7/8.8.7) with SMTP id RAA13435 for ; Sun, 28 Mar 1999 17:53:01 -0500 From: Michael Shalayeff Message-Id: <199903282252.RAA22833@lucifier.dial-up.user.akula.net> Subject: Re: [hppa-linux] Qn on PA-RISC Page tables and TLB In-Reply-To: from Kumar at "Mar 28, 99 12:37:05 pm" To: hppa-linux@thepuffingroup.com Date: Sun, 28 Mar 1999 17:52:49 -0500 (EST) Cc: hppa-linux@thepuffingroup.com Reply-To: mickey@openbsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-ID: Making, drinking tea and reading an opus magnum from Kumar: > > On Thu, 25 Mar 1999, Craig Hada wrote: > > > > > > > In the absense of a harware TLB walker, the page directory format can be > > structured by software to fit its needs. However, the TLB miss handler > > must reformat the bits to fit the format of the TLB insert instructions. > > To get maximum performace from the system, the TLB miss handlers must be > > made very efficient. The format of the page directory entry in the PA-RISC > > Arch 1.1 book minimizes the work of the TLB miss handlers by aligning the > > fields to match the format of the TLB insert instructions. > > > > > > > Is it necessary that the virtual to physical mappings in TLB be inserted > only in a tlb miss fault. Can I insert entries in the anticipation that > there will be a fault soon, for example when I first enable > virtual mode ? If not, there is a potential chicken and egg problem > because I will get a TLB miss fault as soon as I turn virtual mode on and > TLB miss fault handler has to run in virtual mode with translations > on.....and there aint any tranlations yet inserted ...you get the pitcure usually kernel (and tlb miss handler) get block-mapped w/ block tlb, so the whole kernel text+data get mapped once w/ one big tlb entry, and won't get no tlb misses for it no more. so, the chicken gonna be ok. cu -- paranoic mickey (my employers have changed but, the name has remained)