Date: Fri, 12 Jul 1996 10:57:14 -0500 (EST) From: John Dyson <dyson@dyson.iquest.net> To: fqueries@jraynard.demon.co.uk (James Raynard) Cc: jpbelang@crim.ca, freebsd-questions@freebsd.org Subject: Re: kernel malloc question Message-ID: <199607121557.KAA02358@dyson.iquest.net> In-Reply-To: <199607102232.WAA04010@jraynard.demon.co.uk> from "James Raynard" at Jul 10, 96 10:32:41 pm
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> > > This is a beginner device driver question: > > The kernel malloc returns physical memory (non swappable), right? > > Yes, all memory used by the kernel is non-pageable, although changing > this is on the wish-list. > Well, actually, you can use kmem_alloc_pageable to get pageable kernel memory. You have to be careful to have process context when page faulting. For a complete implementation of how to do kernel pageable memory, I refer you to the sys_pipe.c in -current. The pipe buffers are pageable. Also, the arg list temporary space in kern_exec is also pageable. You are absolutely right about the malloc() stuff being non-pageable though. Sorry that I have not responded sooner, I read my mail at work, file it and am sometimes rude and forget it it :-(. I apologize. John
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