Date: Thu, 30 Jan 2003 17:46:28 -0700 From: Scott Long <scott_long@btc.adaptec.com> To: Terry Lambert <tlambert2@mindspring.com> Cc: Julian Elischer <julian@elischer.org>, David Schultz <dschultz@uclink.berkeley.edu>, "Andrew R. Reiter" <arr@watson.org>, arch@freebsd.org Subject: Re: PAE (was Re: bus_dmamem_alloc_size()) Message-ID: <3E39C764.3070500@btc.adaptec.com> In-Reply-To: <Pine.BSF.4.21.0301301059310.35796-100000@InterJet.elischer.org> References: <Pine.BSF.4.21.0301301059310.35796-100000@InterJet.elischer.org> <3E39B52E.E46AF9EA@mindspring.com>
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Terry Lambert wrote: > Julian Elischer wrote: > > >The reason for PAE is simple. > > > >Disk caches need not be in mapped memory. Physical memory will do. > >If you want to cache more than 4GB, then PAE is an effective answer. > > > >(Assuming I have my TLAs the right way around..) > > > Using the memory by declaring a small copy window that's accessed > via PAE in the kernel, and not really supporting PAE at all, can > make this work... [...] > > -- Terry This troll is totally unneccessary. Making peripheral devices work with PAE is a matter handled between the device driver and the busdma system. Drivers that cannot pass 64 bit bus addresses to their hardware will have the data bounced by busdma, just like what happens in the ISA world. The whole point of the busdma push that Robert and Maxime started a few months ago is to prepare drivers for the possible coming of PAE. Honestly, though, if you're going to spend the money on a PAE-capable motherboard and all the memory to go along with it, are you really going to put a Realtek nic and an Advansys scsi card into it? Also, the PAE work that might happen is not going to affect the vast majority of FreeBSD/i386 users at all; I can only imagine that it will be a config(8) option that will most likely default to 'off'. There is nothing to bikeshed here. Please respect that there are people who need PAE, understand PAE, and will happily accept PAE. Those who do not need, understand, or accept it can go along with their lives blissfully happy with it turned off. Scott To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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