cause a problem of spiraling death due to buffer resource limitations.
The vfs_bio code in general had little ability to handle buffer resource
management, and now it does. Also, there are a lot more knobs for tuning the
vfs_bio code now. The knobs came free because of the need that there
always be some immediately available buffers (non-delayed or locked) for
use. Note that the buffer cache code is much less likely to get bogged
down with lots of delayed writes, even more so than before.
- OVERRIDE_TUNER: allows you to manually choose the tuner type for those
cards that fail to probe properly. See source for legal
values.
- OVERRIDE_DBX: allows you to manually choose DBX or NO DBX for those
cards that fail to probe properly.
0 == no DBX circuit present, 1 == DBX circuit present.
will see it. The name of the file is obtained by appending ".config"
to the name of the kernel file. If the file doesn't exist, then an
annoying message is printed.
Reduced the command line buffer size yet again from 4096 to 1024. It is
oversized to defend against overrun in gets(), but data space is starting
to run out so the buffer size can't be as grossly oversized as before.
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.
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)
- 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
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
cost since it is only done in cpu_switch(), not for every exception.
The extra state is kept in the pcb, and handled much like the npx state,
with similar deficiencies (the state is not preserved across signal
handlers, and error handling loses state).
