From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4411FB40.3050406@lanl.gov> Date: Fri, 10 Mar 2006 15:18:40 -0700 From: Ronald G Minnich User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) MIME-Version: 1.0 To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu> Subject: Re: [9fans] kernels References: <20060310211652.17E17B4972@dexter-peak.quanstro.net> <20060310220707.GA33767@mero.morphisms.net> In-Reply-To: <20060310220707.GA33767@mero.morphisms.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Topicbox-Message-UUID: 127c75ae-ead1-11e9-9d60-3106f5b1d025 William Josephson wrote: > On Fri, Mar 10, 2006 at 04:31:31PM -0500, jmk@plan9.bell-labs.com wrote: > >>To be fair, it's not the 'standard's that are at fault here. >>Using VESA requires taking the processor out of protected mode >>and jumping into the BIOS and that's difficult with 2 processors >>as we need to make sure they are all agreed on what's going on >>and interrupts are properly disabled, etc. The Plan 9 x86 SMP >>code wasn't written with those goals in mind. It should be possible >>but clearly we didn't get it right and it's a low-priority item. > > > You can also use VM86 mode on 386 (but not AMD/x86-64). > It actually isn't so bad -- I'd have to think it would > be much easier than going back to real mode. Of course, > it isn't an option on 64-bit machines, which may effectively > leave you in the same place. As cool as I think the VESA stuff is, our experience is that it's also a mistake to do it via switch to 16-bit mode. Making it work right gets really tricky, as you just learned with SMP; that's only one possible hazard. We've been enabling graphics with an emulator-based approach for a few years now, and it does work well. Code available in the linuxbios source tree, if anybody wants to mess around with it. thanks ron