It is possible for multiple process to sleep concurrently waiting
for a buffer. When the buffer shortage is a shortage of space but
not a shortage of buffer headers, the processes took turns creating
empty buffers and waking each other to advertise the brelse() of
the empties; progress was never made because tsleep() always found
another high-priority process to run and everything was done at
splbio(), so vfs_update never had a chance to flush delayed writes,
not to mention that i/o never had a chance to complete.
The problem seems to be rare in practice, but it can easily be
reproduced by misusing block devices, at least for sufficently slow
devices on machines with a sufficiently small buffer cache. E.g.,
`tar cvf /dev/fd0 /kernel' on an 8MB system with no disk in fd0
causes the problem quickly; the same command with a disk in fd0
causes the problem not quite as quickly; and people have reported
problems newfs'ing file systems on block devices.
Block devices only cause this problem indirectly. They are pessimized
for time and space, and the space pessimization causes the shortage
(it manifests as internal fragmentation in buffer_map).
This should be fixed in 2.2.
1) fix k1-k4 to match XF3.3
2) fix kb,kD to match keyboard
3) merge xterm-color in: default description must match best current practice
and color card is most common variant for X now. Add xterm-mono entry for
mono cards.
Submitted by: Forgotten
Passed on by: Terry Dwyer 61 8 9491 5161 <tdwyer@io.telstra.com.au>
Also remove extraneous setuid(0) - it's only undone by
the subsequent call to SelectSystem().
should work with no driver changes, though not all features are currently
used.
Remove code that was conditional on NEW_SCSICONF not being defined. This
was temporary code, that at a time got excluded correctly, until the new
scsiconf became the default, and NEW_SCSICONF was no longer specified.
Add support for quirks defined in scsiconf.c. For now only the HP3724/5
needs an entry, since that drive can't be used with tags.
so don't enforce the MTU as an MRU. Allow bidirectional ppp MTU
negotiation, by checking against a differnt figure for MRU.
Make it large enough for ATM frames at least.
Submitted by: archie@whistle.com (archie cobbs)
o Allow "set var" with no args to blank var (don't req "").
o Zero VarTerm ASAP if not in interactive mode.
o Never print anything to stdout in -direct mode.
o Count redial when failing to open modem.
o Increase device size to 40 characters (for host:port).
o Remove missed "if (fd == 0) fd = 1;".
o Don't give up on incoming non-terminal connections.
- Added support for "dual" internal/serial consoles (-D flag). If -D is set,
then all i/o from the boot blocks is to and from both the internal console
and the serial console. -D has no effect on the kernel (-h decides the
kernel serial console as usual). -D should normally be set in /boot.config.
- Get help messages from /boot.help. You should copy boot.help from the
biosboot directory to the root directory on the boot drive when you
install new boot blocks.
- New, less invasive keyboard probe. Enable keyboard probe dynamically (-P
flag). Should probably never be used (use -h instead).
- Fixed/improved initialization from boot.config. It didn't interact correctly
with the NAMEBLOCK option, and the initialization of the drive/unit/partition
didn't stick when a non-default kernel name was entered.
- Don't reset or forget the default drive/unit/... or kernel name so often.
- Set the default kernel name to something unbootable after `?'.
- Display the defaults better.
- Removed PROBE_KEYBOARD_LOCK option (use -h instead).,
- Removed BOOT_FORCE_COMCONSOLE option (use device flag 0x20 instead).
- Removed -a (RB_HALT) flag. This flag is only used for reboots.
Submitted by: about 2/3 by yokota
