Date: Sat, 22 Dec 2007 14:09:14 -0600 From: Joshua Isom <jrisom@gmail.com> To: Bruce Cran <bruce@cran.org.uk> Cc: freebsd-questions@freebsd.org Subject: Re: amd64 native boot loader? Message-ID: <020f211f77887eeb2eb8a03cd825f372@gmail.com> In-Reply-To: <476CD9C9.3090101@cran.org.uk> References: <70f41ba20712211547g74a6a4b0tf08fec8125739a08@mail.gmail.com> <476CD9C9.3090101@cran.org.uk>
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On Dec 22, 2007, at 3:32 AM, Bruce Cran wrote: > AMD64 CPUs are backwards compatible with i386; they boot in 16-bit > real mode and only get switched into 64-bit 'long mode' by the kernel > later on. Since both i386 and amd64 start booting in the same way, > there's no need for separate bootloaders. > > -- > Bruce > I've thought about this too, but do wonder why the boot loader couldn't go into long mode in one of the loader stages. I don't know if there'd be any significant improvements or drawbacks other than duplication of some code(which I imagine isn't changed often). Somewhat offhand, can the OpenBSD loader chain boot FreeBSD? Due to my dvd drive being sata over atapi, it wasn't recognized by the 6 branch until recently(many thanks to whoever committed the change). But I recall that the boot cd for FreeBSD wouldn't boot, but the boot cd for OpenBSD would. Of course that does primarily relate to cdboot and not boot0.
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