bootdir
D1135799889
Aziphos (207.183.171.11)
#In Mid December 2002, a new feature was added to the system. It
#changes the previous #//boot to be a directory rather than a file,
#and allows what used to be a binary that had to be compiled to be a
#script instead.
#
#Russ Cox said something like this in
#[http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&selm=606456fcdc17ce997666a1895d86f9ba%40plan9.bell-labs.com]
#
#There is a new kernel config file section called "bootdir" that
#lists the files to be placed in #//boot. There are no binaries in #/
#itself anymore.
#
#A typical bootdir section might look like
#
#! 	bootdir
#! 		bootpcdisk.out boot
#! 		/386/bin/ip/ipconfig
#! 		/386/bin/auth/factotum
#! 		/386/bin/disk/kfs
#! 		/386/bin/cfs
#
#which says that /boot will contain four files: boot, ipconfig,
#factotum, kfs, and cfs, copied from the listed paths.
#
#The kernels have always special cased boot$CONF.out to get it listed
#as /boot. It is now /boot/boot, and no longer a special case.
#
#Now that everything is in /boot, initcode had to change for all the
#kernels; /boot/boot itself had to change to exec /boot/ipconfig
#(instead of /ipconfig), etc. Finally, auth_getkey changed. It looks
#for /factotum and then /boot/factotum, to deal with either type of
#kernel.
#
#The boot file /386/bin/ip/ipconfig (e.g.) turns into
#_386_bin_ip_ipconfig.root.s and then _386_bin_ip_ipconfig.root.8.
#It's a bit of an ugly name, but mk clean will get rid of them. You
#could imagine just using the last path element, but that might lead
#to weird build inconsistencies if kernels were using two different
#files with the same last element. One unfortunate consequence of the
#big name is that _386_bin_auth_factotum.root.s is too long for the
#current file servers to deal with. You could use lnfs to get around
#this, but I didn't want to require lnfs(4) for the kernel build, so
#we have a rule in portmkfile that copies factotum and ipconfig to
#factotum.hack and ipconfig.hack and then the bootdir section
#actually looks like:
#
#! 	bootdir
#! 		bootpcdisk.out boot
#! 		ipconfig.hack ipconfig
#! 		factotum.hack factotum
#! 		/386/bin/disk/kfs
#! 		/386/bin/cfs
#
#sadly. That will go away when we get long file names.
#
#The pc initcode is also changed. Whereas before it used to do
#
#! 	exec("/boot", ["boot", 0]);
#
#in hand-coded assembly (pc/initcode.s), it now does
#
#! 	open("#c/cons", OREAD);
#! 	open("#c/cons", OWRITE);
#! 	open("#c/cons", OWRITE);
#! 	bind("#c", "/dev", MAFTER);
#! 	bind("#ec", "/env", MAFTER);
#! 	bind("#e", "/env", MCREATE|MAFTER);
#! 	bind("#s", "/srv", MREPL|MCREATE);
#! 	execl("/boot/boot", "/boot/boot", 0);
#
#in C (port/initcode.c). The point is to set up enough of a namespace
#that /boot/boot can be a shell script. Eventually the other
#architectures should change too, though it's not urgent. If someone
#wants to do the bitsy, send me mail and I'll let you know what it
#took to get one of the old undistributed mips kernels changed over.
#(The compiler setup is similar.)
#
#As a much bigger example, I built a kernel called pcext the other
#night. It uses rx and trampoline to connect through a Plan 9 gateway
#machine to the root file server. It uses this bootdir:
#
#! 	bootdir
#! 		bootext boot
#! 		/386/bin/rc
#! 		/rc/lib/rcmain
#! 		/386/bin/bind
#! 		/386/bin/cat
#! 		/386/bin/cp
#! 		/386/bin/echo
#! 		/386/bin/mount
#! 		/386/bin/sleep
#! 		factotum.hack factotum
#! 		/386/bin/ip/ipconfig
#! 		/386/bin/cfs
#! 		/386/bin/aux/srvthru
#
#(and does require lnfs to build).
#
#Srvthru is the obvious program -- it connects to rx, authenticates,
#starts trampoline to the real file server, and then optionally
#pushes cfs onto the connection.
#
#The point is that bootext is a shell script, which makes it easier
#to tweak than when /boot was a binary building out of
#/sys/src/9/boot.
#
#! 	#!/boot/rc -m /boot/rcmain
#! 	
#! 	cd /boot
#! 	cp '#r/rtc' '#c/time'
#! 	bind -a /boot /bin
#! 	bind -a '#I' /net
#! 	bind -a '#l0' /net
#! 	bind -a '#S' /dev
#! 	bind '#p' /proc
#! 	bind '#d' /fd
#! 	bind -a /boot /
#! 	ipconfig
#! 	echo 'authdom=cs.bell-labs.com auth=204.178.31.3' >>/net/ndb
#! 	factotum -sfactotum -u -a 204.178.31.3
#! 	cargs=()
#! 	if(~ $#cfs 1 && ! ~ $cfs off)
#! 		cargs=(-c $cfs)
#! 	srvthru $cargs tcp!204.178.31.2!17009 il!emelie!9fs boot emelie
#! 	mount -c /srv/boot /root
#! 	bind -ac /root /
#! 	bind -c /root/mnt /mnt
#! 	mount -a '#s/factotum' /mnt
#! 	rootdir=/root
#! 	rootspec=''
#! 	/386/init -t
#! 	/boot/rc -m/boot/rcmain -i	# in case init fails
#
#It takes care of everything /boot traditionally does, using srvthru
#as the way to establish /srv/boot (and also /srv/emelie, just for
#kicks).
#