From mboxrd@z Thu Jan 1 00:00:00 1970 In-Reply-To: Date: Thu, 16 Sep 1999 12:47:15 +0200 To: Geert Uytterhoeven , linuxppc-dev@lists.linuxppc.org From: Benjamin Herrenschmidt Subject: Re: New booter Message-Id: <19990916124715.021257@mailhost.mipsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Thu, Sep 16, 1999, Geert Uytterhoeven wrote: >After compiling a new kernel, I copy it to /boot (using a new name, of >course), >update the symlinks and rerun LILO. If I forget (one of) the last two steps, >nothing bad happens. > >IMHO the best thing would be something like MILO on the Alpha. MILO is a >small binary that contains device drivers and filesystems taken from the >standard Linux kernel sources. Hence MILO knows about e.g. your ext2fs >partition and fancy U2W-SCSI adapter. On Alpha the MILO binary is put on a >MSDOS formatted partition. On PPC, you could store it on either a HFS or MSDOS >formatted partition, or use a LILO-alike scheme (raw-blocks). Even BootX could >load MILO under MacOS, if you want that. > >Combined, you would have a shared `high-level' booter, which is called by >different `low-level' booters (FS (HFS/MSDOS), raw-blocks, BootX), depending >on >your taste and architecture: I personally tend to think that the small HFS partition is not a so bad idea. As several person pointed out, the boot block mecanism involves fitting most of the primary booter in a small space, requires building a map of the files it must access to, etc... With a firmware able to load files from a simple file system, eventually hidden from users, makes things a lot easier, you don't have to rebuild maps each time you change a file, you can split your booter into several files if you want to, etc... For example, under linuxppc, we could mount this bootstrap HFS partition on /boot, and just copy kernel to this in order to make them available to the booter. Of course, all this is specific to PowerMacs, other PPC machine needs a different boot mecanism anyway. Back to miBoot, I'll try to get it working first (it seems to work but the kernel hangs, I don't know why yet and I won't have time to look into this until this week-end). It doesn't solve all the problems since making bootable CDs (which is my main goal for now) requires a valid driver on the CD (only MacOS Toast can do that to my knowledge) and using this trick to boot from the HD also requires a valid MacOS driver on the disk. I do have some plans to extend the mecanism further and make a CD driver to avoid relying on Toast and eventually a hard disk driver too (I do have a prototype SCSI driver but this requires licenced patches from Apple to make something really useable). -- Perso. e-mail: Work e-mail: BenH. Web : ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/