I have been experimenting with union mounts today with a recent -stable (cvsupped yesterday), and I haven't had much luck.
Because cvsup likes to obliterate local changes, I thought it would be convenient to keep the altered files on a separate filesystem and use a union mount to overlay them on the upstream source when I compile things. So: # mount /dev/da0s1a on / (local, writes: sync 420 async 3185) procfs on /proc (local) /dev/da0s1e on /www (local, writes: sync 2 async 0) # mount /dev/da0s1f /srcdelta # ls -l /srcdelta total 1 drwxr-xr-x 6 root wheel 512 Feb 18 10:32 sys # umount /srcdelta # ls /usr/src COPYRIGHT UPDATING include share CVS bin kerberosIV sys Makefile contrib lib tools Makefile.inc0 crypto libexec usr.bin Makefile.inc1 etc release usr.sbin Makefile.upgrade games sbin README gnu secure # mount -o union /dev/da0s1f /usr/src # ls -l /usr/src total 1 drwxr-xr-x 6 root wheel 512 Feb 18 10:32 sys # umount /usr/src # uname -a FreeBSD shirt.www.demon.net 3.1-STABLE FreeBSD 3.1-STABLE #6: Thu Feb 18 02:26:59 GMT 1999 r...@shirt.www.demon.net:/usr/src/sys/compile/SHIRT i386 # However, on another machine running 3.0-RELEASE mount -o union works as expected: # ls -l total 6 drwxr-xr-x 2 root wheel 512 Feb 18 16:36 da1 drwxr-xr-x 2 root wheel 512 Dec 11 11:06 da2 # mount /dev/da1s1e da1 # mount /dev/da2s1e da2 # ls -l da?/* -rw-r--r-- 1 root wheel 0 Feb 18 16:36 da1/this_is_da1 -rw-r--r-- 1 root wheel 0 Feb 18 16:36 da2/this_is_da2 # umount da2 # mount -o union /dev/da2s1e /www/da1 # ls -l da?/* -rw-r--r-- 1 root wheel 0 Feb 18 16:36 da1/this_is_da1 -rw-r--r-- 1 root wheel 0 Feb 18 16:36 da1/this_is_da2 # Shirt's kernel configuration is below. Tony. -- f.a.n.finch d...@dotat.at f...@demon.net machine "i386" cpu "I686_CPU" ident SHIRT maxusers 64 options INET #InterNETworking options FFS #Berkeley Fast Filesystem options FFS_ROOT #FFS usable as root device [keep this!] options MFS #Memory Filesystem #options MFS_ROOT #MFS usable as root device, "MFS" req'ed options NFS #Network Filesystem options NFS_NOSERVER #options NFS_ROOT #NFS usable as root device, "NFS" req'ed options MSDOSFS #MSDOS Filesystem #options "CD9660" #ISO 9660 Filesystem #options "CD9660_ROOT" #CD-ROM usable as root. "CD9660" req'ed options PROCFS #Process filesystem options "COMPAT_43" #Compatible with BSD 4.3 [KEEP THIS!] options SCSI_DELAY=1000 #Be pessimistic about Joe SCSI device options UCONSOLE #Allow users to grab the console options USERCONFIG #boot -c editor options VISUAL_USERCONFIG #visual boot -c editor options NETALIAS options NETBIND options SOFTUPDATES options "MAXMEM=(64*1024)" options PQ_MEDIUMCACHE options INCLUDE_CONFIG_FILE options PERFMON options IPFIREWALL options IPFIREWALL_VERBOSE options IPFIREWALL_DEFAULT_TO_ACCEPT options ICMP_BANDLIM options DUMMYNET config kernel root on wd0 controller isa0 controller eisa0 controller pci0 controller fdc0 at isa? port "IO_FD1" bio irq 6 drq 2 disk fd0 at fdc0 drive 0 #disk fd1 at fdc0 drive 1 options "CMD640" # work around CMD640 chip deficiency controller wdc0 at isa? port "IO_WD1" bio irq 14 disk wd0 at wdc0 drive 0 options ATAPI #Enable ATAPI support for IDE bus options ATAPI_STATIC #Don't do it as an LKM device acd0 #IDE CD-ROM controller ncr0 controller scbus0 device da0 device pass0 device cd0 #Only need one of these, the code dynamically grows # atkbdc0 controlls both the keyboard and the PS/2 mouse controller atkbdc0 at isa? port IO_KBD tty device atkbd0 at isa? tty irq 1 device psm0 at isa? tty irq 12 device vga0 at isa? port ? conflicts # splash screen/screen saver #pseudo-device splash #options VM86 #options VESA # syscons is the default console driver, resembling an SCO console device sc0 at isa? tty device npx0 at isa? port IO_NPX irq 13 # Laptop support (see LINT for more options) # device apm0 at isa? disable flags 0x31 # Advanced Power Management # serial port device sio0 at isa? port "IO_COM1" flags 0x10 tty irq 4 device sio1 at isa? port "IO_COM2" tty irq 3 # Parallel port device ppc0 at isa? port? net irq 7 controller ppbus0 device nlpt0 at ppbus? device plip0 at ppbus? device ppi0 at ppbus? #controller vpo0 at ppbus? # Order is important here due to intrusive probes, do *not* alphabetize # this list of network interfaces until the probes have been fixed. # Right now it appears that the ie0 must be probed before ep0. See # revision 1.20 of this file. device tl0 device tx0 pseudo-device loop pseudo-device ether pseudo-device sl 1 pseudo-device ppp 1 pseudo-device tun 1 pseudo-device pty 32 pseudo-device gzip # Exec gzipped a.out's pseudo-device vn # KTRACE enables the system-call tracing facility ktrace(2). # This adds 4 KB bloat to your kernel, and slightly increases # the costs of each syscall. options KTRACE #kernel tracing # This provides support for System V shared memory and message queues. # options SYSVSHM options SYSVMSG # The `bpfilter' pseudo-device enables the Berkeley Packet Filter. Be # aware of the legal and administrative consequences of enabling this # option. The number of devices determines the maximum number of # simultaneous BPF clients programs runnable. pseudo-device bpfilter 4 #Berkeley packet filter To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-current" in the body of the message
