Date: Thu, 06 Dec 2001 09:24:58 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Nate Williams <nate@yogotech.com> Cc: freebsd-hackers@FreeBSD.ORG, Ronald G Minnich <rminnich@lanl.gov> Subject: Re: Re[2]: switching to real mode Message-ID: <XFMail.011206092458.jhb@FreeBSD.org> In-Reply-To: <15375.42185.608553.610033@caddis.yogotech.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 06-Dec-01 Nate Williams wrote: >> > I saw an example of switching in real mode in linux' sources (it looks >> > pretty clear) and thouhgt it is possible to do the same under FreeBSD. >> > The problem is I'm absolutely lost in FreeBSD's physical memory management >> > implementation (page tables and directory and so on). >> >> That code is quite broken. You need to check out the ones I mentioned >> earlier. All that the code does in the linux kernel is fail badly. >> >> Actually there used to be in freebsd some really nice code for popping >> into real mode and back again. It was to support calling BIOS for certain >> things. > > I believe the code is still there, and it's used for APM bios calls, > if I remember correctly. It uses VM86 mode, not real mode. Going back and forth to real mode is too expensive. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?XFMail.011206092458.jhb>