Date: Fri, 3 Sep 1999 14:46:45 -0500 From: "Jason" <jes@hal-pc.org> To: <freebsd-sparc@freebsd.org> Subject: Re: Status of FBSD sparc porting? Message-ID: <008d01bef645$0efb9e60$0500a8c0@local.nullifier.dyn.ml.org> References: <199909012314.TAA11490@weedcon1.cropsci.ncsu.edu> <37CFC28D.7063AF7A@post.rwth-aachen.de> <19990903120227.07974@hydrogen.fircrest.net>
next in thread | previous in thread | raw e-mail | index | archive | help
> Gerald Heinig scribbled this message on Sep 3: > > 1) Is it better/more sensible to use the NetBSD code or even Linux stuff > > to find out how to do things or is it better to get your own docs and > > solve the problem yourself? Personally, I'd much prefer to "roll our > > own", although it's probably far more work and considerably more > > difficult. However, we'd all learn more that way. Anyone have any ideas > > on this? > > well, if you followed suite, dfr based the alpha port off of netbsd > code... which seems to of work pretty well... It would be best if you (Gerald Heinig) use any resources at your disposal. It won't prevent anyone, even you, from writing it from scratch. The only info I've found to a specific MMU is for the ss2 at http://choices.cs.uiuc.edu/cs423/sparc/index.html, and then I don't know if it is accurate. > > 3) Is there a rough overview of what happens and where, when the FreeBSD > > kernel starts up? I'm looking for something like the description of the > > Minix source code in Andrew Tanenbaum's "Operating systems: design and > > implementation". The book by Karels/McKusick/Bostic/Quarterman is too > > high-level (ie. not enough detail) and the source code is too much > > detail. > > Does something like this exist? > > the FreeBSD kernel starts up in sys/kern/init_main.c... the function > that starts everything off used to be call main, but it was reciently > changed to mi_startup (r1.120)... that function is basicly just a sort > function to sort all the sysinit's and then run them... (hmmm.. that's > right, I was going to write a function to start up sysinit's so that we > didn't have the code duplicated in the kld loader)... > > so, REALLY what you need to do is look at the order in which the > sysinit's get run... > -- > John-Mark Gurney Voice: +1 541 684 8449 > Cu Networking P.O. Box 5693, 97405 Actully, it starts in src/sys/ARCH/ARCH/lcore.s::btext, which the loader calls. lcore calls src/sys/kern/init_main.c::mi_startup when it is done. You might as well step through a port starting with its lcore.s. The source is reather easy to follow. Besides, you need to anyway if you are thinking of writing a port. I'm missing the step between the boot loader starting the kerenl, but here goes a short summary (in other words, 'take with a grain of salt'/look for yourself) based on /i386-current. The boot loader's entry point into the kernel is in src/sys/i386/i386/lcore.s. Somewhere the loader calls/steps into the function btext. lcore goes through the motions, setting up the machine specific things, such as: init'ing BIOS settings setting up the kdb throughout getting the boot info from the loader (cookies) figures out the cpu vender/model starts allocating structs based on KERNBASE initial pmap structs (page tables) and sets up the MMU sets up the boot stack calls src/sys/kern/init_main.c::mi_startup() which starts running sysinit/KLD subsystems You can find the subsystems but a simple 'grep -R SYSINIT *' or better yet, set up gtags and do a 'global SYSINIT'. The next thing is the order of executions. You can find those in src/sys/sys/kernel.h::sysinit_sub_id. Of course the first thing its got to do is set up the console, then you see the copyright notice, after which it sets any tunable variables, VM, KVM, prints cpu info, sets up KLD's, init (proc 0), etc. That should be enought to get you started. See, the source isn't that hard to follow. - Jason To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-sparc" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?008d01bef645$0efb9e60$0500a8c0>