"It would be good to point out that a machine that only has SCSI devices
may also generate this message if an IDE CD-ROM is not configured as
the Master device. Words like these might work ..."
This generally means that there is no CDROM in the CDROM drive,
or the drive is not visible on the bus. Feed the drive
something, and/or check it's master/slave status.
Submitted by: Neil Smith <ngs@sesame.hensa.ac.uk> with a small addition
of delta's to be mailed out every hour (or however often you schedule
the cron job).
ctm_dequeue is the cron job which takes the stuff from the
queue directory and punts it into sendmail. The chunks of
the deltas (and the complete deltas if they are that small)
are sorted into order before being dispatched, so the people
subscribing should still get the bits in the right order.
The changes to ctm_smail should be fairly safe as they won't be
activated unless you go for the new queue directory option.
option to pwd_mkdb and adding this option to utilities invoking it.
Further, the filling of both the secure and insecure databases has been
merged into one loop giving also a performance improvemnet.
Note that I did *not* change the adduser command. I don't read perl
(it is a write only language anyway).
The change will drastically improve performance for passwd and
friends with large passwd files. Vipw's performance won't change.
In order to do that some kind of diff should be made between the
old and new master.passwd and depending the amount of changes, an
incremental or complete update of the databases should be agreed
upon.
Testing with the high frequency of 20000 Hz (to find problems) only found
the problem that this frequency is too high for slow i386's.
Disable interrupts while setting the timer frequency. This was unnecessary
before rev.1.57 and forgotten in rev.1.57. The critical (i8254) interrupts
are disabled in another way at boot time but not in the sysctl to change
the frequency.
sleeps before being swapped out. The time is increased from 4 secs to
10 secs. Originally I had decreased it from 20 to 4, but that is a bit
severe. 20 is too long though.
The i386 pmap module uses a special area of kernel virtual memory for mapping
of page tables pages when it needs to modify another process's virtual
address space. It's called the 'alternate page table map'. There is only one
of them and it's expected that only one process will be using it at once and
that the operation is atomic.
When the merged VM/buffer cache was implemented over a year ago, it became
necessary to rundown VM pages at I/O completion. The unfortunate and
unforeseen side effect of this is that pmap functions are now called at bio
interrupt time. If there happend to be a process using the alternate page
table map when this I/O completion occurred, it was possible for a different
process's address space to be switched into the alternate page table map -
leaving the current pmap process with the wrong address space mapped when
the interrupt completed. This resulted in BAD things happening like pages
being mapped or removed from the wrong address space, etc.. Since a very
common case of a process modifying another process's address space is during
fork when the kernel stack is inserted, one of the most common manifestations
of this bug was the kernel stack not being mapped properly, resulting in a
silent hang or reboot. This made it VERY difficult to troubleshoot this bug
(I've been trying to figure out the cause of this for >6 months). Fortunately,
the set of conditions that must be true before this problem occurs is
sufficiently rare enough that most people never saw the bug occur. As I/O
rates increase, however, so does the frequency of the crashes. This problem
used to kill wcarchive about every 10 days, but in more recent times when
the traffic exceeded >100GB/day, the machine could barely manage 6 hours of
uptime.
The fix is to make certain that no process has the pages mapped that are
involved in the I/O, before the I/O is started. The pages are made busy, so
no process will be able to map them, either, until the I/O has finished.
This side-steps the issue by still allowing the pmap functions to be called
at interrupt time, but also assuring that the alternate page table map won't
be switched.
Unfortunately, this appears to not be the only cause of this problem. :-(
Reviewed by: dyson
Expand definition of 'established' and 'icmptypes.' Correct examples
which still used the old syntax. Add a pointer to the CERT packet
filtering checklist.
Prevent ALL protocol from being used with port specifications.
Allow 'via' keyword at any point in the options list. Disallow
multiple 'via' specifications.
