loader and ifconfig_*_name problem in 6.1-STABLE of 5 June

[Hiroo Ono]

I upgraded via build/installworld from 6.1-PRERELEASE as of 27 Mars
to 6.1-STABLE 5 June, and encounterd 2 problems.

a) loader and kernel has some problem that lead to instant reboot upon
  loading the kernel.
  the problem was as follows:
  1) booting the new kernel with the old loader was fine.
    I did buildkernel and installkernel and rebooted in single user mode.
    It had no problems.
  2) loading the new kernel with the new loader made the machine reboot.
    After step (1), I did installworld and rebooted.
    It resulted in rebooting just after loader menu.
    I could escape to loader prompt and found that doing
    > unload
    > load kernel
    makes the machine reboot.
  3) loading the old kernel with the new loader can boot in single
    user mode.
    > unload
    > set module_path=/boot/kernel.old
    > load kernel
     (and some other necessary modules)
    > boot -s
    was fine (though, exiting in multi-user mode had problem around
    mountd and panic'ed with the new userland).

  I copied the old /boot/loader.old to /boot/loader as a workaround.
  I have
    CFLAGS= -O2 -pipe
    COPTFLAGS= -O2 -pipe
  and no CPUTYPE setting in /etc/make.conf, so I wonder what caused
  the problem.

b) pre-loading ng_ether.ko module and doing ifconfig name may
  have problem with ppp.

  I put the following in /etc/rc.conf
    ifconfig_sis0_name="net0"

  and changed device setting in /etc/ppp/ppp.conf as follows:
    set device PPPoE:net0

  This did not work and had the following error message in /var/log/messages:
    ppp[258]: tun0: Warning: net0: Cannot send a netgraph
    message: No such file or directory

  changing device setting to
    set device PPPoE:sis0

  or doing
    ngctl name sis0: net0

  could make ppp work.

  The problem may be caused by loading ng_ether.ko in loader.conf
  (I do not remember why I did this, though).
  If I did not do that, ng_ether module was loaded when ppp was invoked
  after interface rename and might have no problem.
  I did not verify this yet, though.