Date: Thu, 16 Apr 1998 13:26:17 -0700 From: Mike Smith <mike@smith.net.au> To: Bernie Doehner <bad@ece.WPI.EDU> Cc: Mike Smith <mike@smith.net.au>, hackers@FreeBSD.ORG, buaas@wireless.net, bad@wireless.net Subject: Re: Documentation of 2.2.5-RELEASE and 3.0 memory protection? Message-ID: <199804162026.NAA01011@dingo.cdrom.com> In-Reply-To: Your message of "Thu, 16 Apr 1998 16:22:40 EDT." <Pine.OSF.3.96.980416160956.31725I-100000@taz.WPI.EDU>
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> > If you want to access memory on an expansion card in the ISA "hole", > > you need to memory-map it into your process. You need a cooperative > > driver for this - syscons allows you to memory-map video memory, and > > AFAIR it's not too picky about the offset you specify. > > But I don't see that being done in practice (or I wasn't able to wind my > way through the kernel sources - probably more likely)... I compared the > if_ed driver (some cards use shared memory, but in the ISA hole of > A0000-100000), to the Digiboard driver (which I thought uses shared > memory, but BELOW A0000). I don't understand you here - drivers are *inside* the kernel, and behave completely differently to user-mode programs. > The Digiboard driver pmap_mapdev's the address, but if_ed does NOT.. > > Our shared memory is in the ISA hole and we currently do not pmap_mapdev. > > buaas@wireless.net has also written another driver (for Dianatel > switch) which lived in monochrome memory, and he also didn't mmap and it > seemed it worked ok. Are you writing a driver, or a user-mode program? This is a critical difference. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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