Date: Sun, 20 Mar 2011 17:06:00 -0500 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: freebsd-ppc@freebsd.org Subject: Re: PowerPC, gpart and multiboot (Was: Trying to install FreeBSD 8.2-RC1 on a PowerMac G5) Message-ID: <4D867A48.50408@freebsd.org> In-Reply-To: <20110320230002.1d23e985.torfinn.ingolfsen@broadpark.no> References: <20110113220450.57d09983.torfinn.ingolfsen@broadpark.no> <AANLkTi=6ma_3o9wvoOH92LPk7j1FUa7y=KpsmtAymmGg@mail.gmail.com> <20110114221406.34969090.torfinn.ingolfsen@broadpark.no> <4D31582F.1060300@FreeBSD.org> <20110115190637.7ac32abe.torfinn.ingolfsen@broadpark.no> <AANLkTimBYrU=2=z%2BjscSmcSFO0mF3OGgkc2CU4EcVpcy@mail.gmail.com> <20110122200810.2386cbef.torfinn.ingolfsen@broadpark.no> <20110313221425.a8d3361f.torfinn.ingolfsen@broadpark.no> <4200D52B-ED04-4F6A-BA2A-EAD7DF3EBF37@gmail.com> <20110314212840.91564b62.torfinn.ingolfsen@broadpark.no> <AANLkTi=na4swbiU6L7gJ7Xhb0QRaMfxXxByRy=xzu-Z0@mail.gmail.com> <AANLkTinsDODsYGgeQezo8rged6khBkVyB=H=ggo7iFoF@mail.gmail.com> <20110318200242.f957f677.torfinn.ingolfsen@broadpark.no> <AANLkTi=SBKMKqpNC-J3qJW_QYOO4uWE5rrie-9K-y-j-@mail.gmail.com> <20110320230002.1d23e985.torfinn.ingolfsen@broadpark.no>
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On 03/20/11 17:00, Torfinn Ingolfsen wrote: > Anyway, here is my plan for multiboot: > root@kg-g5# gpart show ad0 > => 18 625142430 ad0 APM (298G) > 18 1600 1 apple-boot (800K) > 1618 155189248 2 freebsd-ufs (74G) > 155190866 8388608 3 freebsd-swap (4.0G) > 163579474 1600 4 apple-boot (800K) > 163581074 155189248 5 freebsd-ufs (74G) > 318770322 306372126 - free - (146G) > > The boot code in partition 4 (ad0s5) will be modified so that it boots from > the next partition (the partition after the one the bootcode itself is loaded from) > instead of the first partition. Do you think it's doable? > > I have examined boot1.c (in /usr/src/sys/boot/powerpc/boot1.chrp) but I don't > really understand how it is finding the partition to boot / load the kernel from. > > Can anyone explain it? I wrote it, so hopefully I can provide some insight. At line 423 of boot1.c, it loops through the first 16 (arbitrary) partitions on the device from which it was booted, then tries to find loader on the first UFS partition it can mount. This isn't actually a good algorithm, but it works pretty well. Making it choose the first following UFS partition might be a good idea, or do something useful with its arguments. -Nathan
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