essential when I fix excessive wakeups for output-below-low-water.
In cy.c and sio.c, wake up via the driver start routine to also
eliminate duplicated code involving the clearing of TS_TTSTOP.
Always (except in code to be replaced soon) call driver start
routine directly instead of going through ttstart().
ttwwakeup(). The conditions for doing the wakeup will soon become
more complicated and I don't want them duplicated in all drivers.
It's probably not worth making ttwwakeup() a macro or an inline
function. The cost of the function call is relatively small when
there is a process to wake up. There is usually a process to wake
up for large writes and the system call overhead dwarfs the function
call overhead for small writes.
no ports are active, provided there are no polled ports and no
`LOSESOUTINTS' ports. Do a little more in the interrupt handler instead.
This is a little less efficient if there are are many active ports but
a little more efficient otherwise. Polled ports are ones with no irq
specified (as before). `LOSESOUTINTS' ports are ones with 0x08 set in
their config flags. Unless this flag is set, it will now take up to one
second to recover from lost output interrupts, if any. Some 8250s and
16450s lose output interrupts.
Improve output buffering: copy the clist buffer to 2 linear buffers if
necessary and possible instead of to 1. Handle an arbitrary queue of
buffers in the interrupt handler. Check for waking up sleepers after
copying characters out of the clist buffer instead of before.
Delay translation of TIOCM_DTR to MCR_DTR etc. so that the top level
routines are more machine independent.
Fix bogus device register in unused code.
Dropping into the debugger when a break comes down the serial line is a
>MISFEATURE (1st class)< and has been put under it's own #ifdef. This
should be a magic sequence of chars instead.
For those where it was easy, drivers were also fixed to call
dev_attach() during probe rather than attach (in keeping with the
new design articulated in a mail message five months ago). For
a few that were really easy, correct state tracking was added as well.
The `fd' driver was fixed to correctly fill in the description.
The CPU identify code was fixed to attach a `cpu' device. The code
was also massively reordered to fill in cpu_model with somethingremotely
resembling what identifycpu() prints out. A few bytes saved by using
%b to format the features list rather than lots of ifs.
old type (stty) ioctls can easily bypass locking bits.
It involves manual conversion from old ioctls to new ones,
large piece of code duplicated from tty_compat.c
after ttioctl too, because it can change t_line.
Remove (TS_CNTTB | TS_LNCH) test, it is always inherits from
old tty mode and can't be reach in currently setted mode.
if (tp->t_line != 0)
test when CS_ODONE, it fails for NTTYDISC, use
if (linesw[tp->t_line].l_start != ttstart)
instead.
Reviewed by:
Submitted by:
Obtained from:
CVS:
BREAK/parity/framing errors.
Term "correctly" assumes POSIX spec. and 4.4 ttyinput() behaviour.
1) Discard BREAK/parity at interrupt level when apropriate IGN*
is set in iflag. It helps "raw" mode works even IGN* is set.
2) Zero parity (if INPCK) and framing directly in buffer
before passing it to b_to_q() in "raw" mode.
Efficency:
interrupt level: if no error occurse, only two "test" commands added
"raw" mode: buf scan incc times for parity/framing added
Reviewed by:
Submitted by:
Obtained from:
CVS:
(a) bring back ttselect, now that we have xxxdevtotty() it isn't dangerous.
(b) remove all of the wrappers that have been replaced by ttselect
(c) fix formatting in syscons.c and definition in syscons.h
(d) add cxdevtotty
NOT DONE:
(e) make pcvt work... it was already broken...when someone fixes pcvt to
link properly, just rename get_pccons to xxxdevtotty and we're done
is close to 1000000 / 960 usec so the confusion probably didn't matter.
Test for COMCONSOLE before testing for RB_SERIAL so that the RB_SERIAL
test can be optimized away if COMCONSOLE is 1.
Simplify and Uniformize style of previous commit.
(b) add a function callback vector to tty drivers that will return a pointer
to a valid tty structure based upon a dev_t
(c) make syscons structures the same size whether or not APM is enabled so
utilities don't crash if NAPM changes (and make the damn kernel compile!)
(d) rewrite /dev/snp ioctl interface so that it is device driver and i386
independant
Obtained from:
sio.c and sioreg.c changed to allow autodetecting the RB_SERIAL flag
passed by the boot blocks so that the kernel can switch to 'serial
console' mode automagically. 'options COMCONSOLE' can still be specified
to force the kernel to always use the serial port as a console.
CONUNIT and CONADDR can also be specified in the kernel config file
if the user wants to shift the console to a different port.
errors at a lower ipl. clist starvation problems can cause hundreds of
tty buffer overflows per second and logging them all amplified the
problems. This problem was less serious in 1.1.5.
Avoid a race in the check for starting a new block of output. com_events
was sometimes messed up and siopoll() looped endlessly. This bug was
introduced in 2.0.
Clean up previous 2 commits. Rename sio_registerdev() to sioregisterdev()
to match the (bad) surrounding naming conventions. There should be a
generic_registerdev().
and all SCSI devices (except that it's not done quite the way I want). New
information added includes:
- A text description of the device
- A ``state''---unknown, unconfigured, idle, or busy
- A generic parent device (with support in the m.i. code)
- An interrupt mask type field (which will hopefully go away) so that
. ``doconfig'' can be written
This requires a new version of the `lsdev' program as well (next commit).
Fix endless loop in siopoll() for an event on a tty with no tty struct.
Don't generate unwanted interrupts in the serial console driver. These
bugs probably don't matter unless the tty struct is dynamically allocated.
Support polled mode. To use it, leave out the irq and the vector in
the config file. It only causes extra overhead for open polled ports.
The maximum usable speed is approximately 1000 bps for a 16450 and
15000 bps for a 16550.
Other cosmetic changes.
you download the microcode to the DSP everytime you power on your system.
They provide a dos-program to do so, but no other support. This commit adds
code to the sio-driver, which implement an ioctl, which will down-load the
micro-code.
To get this functionality, you must define DSI_SOFT_MODEM.
The program to actually employ the ioctl is not included, but the entire
source looks like this:
#include <sys/ioctl.h>
#include <stdio.h>
main()
{
unsigned char buffer[100000];
int i;
read(0,buffer,100000);
if((i = ioctl(1,TIOCDSIMICROCODE,buffer)) < 0)
perror("ioctl");
return i;
}
And you use it like this:
smload < data144b.dsi > /dev/ttyid3
You need to copy the *.DSI files from the dos-media provide with your modem.
You can see what is downloaded by issuing the ATI3 command to the modem.
DSI's scheme for what code you can run on your modem isn't violated by this.
Poul-Henning Kamp
phk@freefall.cdrom.com
Merged changes from 2.0 version (revisions 1.46-1.50) by hand.
Finished conversion to clists: removed flush of tty output buffer
in comflush() (most writes were truncated to 256 bytes) and restored
bypass of ttyinput() in siopoll().
Finished conversion to 2.0 types - more void *'s, less caddr_t's,
less casts, no Dev_t's.
Only these things are seriously broken now compared with 1.1.5:
waiting for output complete is impossible so ttywait() can deadlock;
sioclose() isn't called enough so sioopen() sometimes returns EBUSY
unnecessarily; input flow control is not implemented.
Added a missing #ifdef INET wrapper in lpt.c
Main change:
Removed the timeout_func_t casts from timeout calls and
correctly defined the timeout routines to conform to
the new format.
lpt.c doesn't have this change.
Reviewed by:
Submitted by:
/usr/src/sys/i386/isa/clock.c:
o Garrett's statclock changes.
o Wire xxxintr, not Vclk.
o Wire using register_intr(), not setidt().
/usr/src/sys/i386/isa/icu.s:
o Garrett's statclock changes.
o Removed unused variable high_imask.
o Fake int 8 for rtc as well as int 0 for clk. Required for kernel
profiling with statclock, harmless otherwise.
/usr/src/sys/i386/isa/isa.c:
o Allow isdp->id_irq and other things in *isdp to be changed by
probes. Changing interrupts later requires direct calls to
register_intr() and unregister_intr() and more care.
ALLOW_CONFLICT_* is brought over from 1.1.5, except
ALLOW_CONFLICT_IRQ is not supported. IRQ conflict checking is
delayed until after probing so that drivers can change the IRQ
to a free one; real conflicts require more cooperation between
drivers to handle.
o Too many details to list.
o This file requires splitting and a lot more work.
/usr/src/sys/i386/isa/isa_device.h:
o Declare more things more completely.
/usr/src/sys/i386/isa/sio.c:
o Prepare to register interrupt handlers as fast.
/usr/src/sys/i386/isa/vector.s:
o Generate entry code for 16 fast interrupt handlers and 16 normal
interrupt handlers. Changed some constants to variables:
# $unit is now intr_unit[intr]. Type is int. Someday it should
be a cookie suitable for the handler (e.g., a struct com_s for
sio).
# $handler is now intr_handler[intr].
# intrcnt_actv[id_num] is now *intr_countp[intr]. The indirection
is required to get a contiguous range of counters for vmstat
and so that the drivers depend more in the driver than on the
interrupt number (drivers could take turns using an interrupt
and the counts would remain correct). There is a separate
counter for each device and for each stray interrupt. In
1.1.5, stray interrupt 7 clobbers the count for device 7 or
something worse if there is no device 7 :-(.
# mask is now intr_mask[intr] (was already indirect).
o Entry points are now _XintrI and _XfastintrI (I = intr = 0-15),
not _VdevU (U = unit).
o Removed BUILD_VECTORS stuff. There's a trace of it left for
the string table for vmstat but config now generates the
string in one piece because nothing more is required.
o Removed old handling of stray interrupts and older comments
about it.
Submitted by: Bruce Evans
``changes'' are actually not changes at all, but CVS sometimes has trouble
telling the difference.
This also includes support for second-directory compiles. This is not
quite complete yet, as `config' doesn't yet do the right thing. You can
still make it work trivially, however, by doing the following:
rm /sys/compile
mkdir /usr/obj/sys/compile
ln -s M-. /sys/compile
cd /sys/i386/conf
config MYKERNEL
cd ../../compile/MYKERNEL
ln -s /sys @
rm machine
ln -s @/i386/include machine
make depend
make
---
This list of changes is in approximately chronological order (oldest first).
o Many cosmetic changes - renamed comintr1 -> siointr1, moved
things around and fixed whitespace.
o Reduced SLIP latency (FRAME_END hack) from 20-30 ms to 16 ms
at 115200 bps (you won't notice the average 10 ms improvement
on slow lines). ppp seems to use only counted transfers so
there's no similar hack available. It's too hard for the
driver to know the count.
o Temporary #ifdefs for new and old interrupt handling
(OLD_INTERRUPT_HANDLING decided by setsofttty() not being
externally defined.
o Don't test for the IIR_NOPEND bit being set - test for the
non-fifo part of the iir equalling it like the docs say to.
States with other IIR_NOPEND set in combination with the
other iir bits are undefined. The docs may be stupid - the
old test would not have broken when the fifo bits were
introduced.
o Noted more problems with DTR wait.
o Rewrote console stuff. Still some initialization and state
preservation problems. Same for kgdb stuff. The driver
doesn't do anything about the console close bug. It needs
to be fixed entirely in i386/cons.c. I like chmr's version
where the the console driver revectors the device open and
close routines.
o Temporary (?) #ifdefs for references to tty buffers.
o Noted further things to do in (2 comments about 3 places) for
phk's change to not touch RTS unless it is being used for flow
control.
o Temporary #ifdefs for timestamp handling. It needs fixing.
The microtime() call breaks the first rule of writing fast
interrupt handlers: NO calls to functions that might do slow
and bad things. microtime() enables interrupts. This turns
out to be only moderately harmful. Also, I want the timestamp
copy outside of the normal interrupt handler.
o Don't init com->tp early for the !DONT_MALLOC_TTYS case -
both sides are NULL.
o Worry about com->tp == NULL in siopoll. I don't see how you
survived the (incc <= 0 || !(tp->state & TS_ISOPEN)) test.
Perhaps early sttys or comcontrols set up the tp's for _all_
the ports before this code is reached.
list of changes, I've made the following additional changes:
1) i386/include/ipl.h renamed to spl.h as the name conflicts with the
file of the same name in i386/isa/ipl.h.
2) changed all use of *mask (i.e. netmask, biomask, ttymask, etc) to
*_imask (net_imask, etc).
3) changed vestige of splnet use in if_is to splimp.
4) got rid of "impmask" completely (Bruce had gotten rid of netmask),
and are now using net_imask instead.
5) dozens of minor cruft to glue in Bruce's changes.
These require changes I made to config(8) as well, and thus it must
be rebuilt.
-DG
from Bruce Evans:
sio:
o No diff is supplied. Remove the define of setsofttty(). I hope
that is enough.
*.s:
o i386/isa/debug.h no longer exists. The event counters became too
much trouble to maintain. All function call entry and exception
entry counters can be recovered by using profiling kernel (the new
profiling supports all entry points; however, it is too slow to
leave enabled all the time; it also). Only BDBTRAP() from debug.h
is now used. That is moved to exception.s. It might be worth
preserving SHOW_BITS() and calling it from _mcount() (if enabled).
o T_ASTFLT is now only set just before calling trap().
o All exception handlers set SWI_AST_MASK in cpl as soon as possible
after entry and arrange for _doreti to restore it atomically with
exiting. It is not possible to set it atomically with entering
the kernel, so it must be checked against the user mode bits in
the trap frame before committing to using it. There is no place
to store the old value of cpl for syscalls or traps, so there are
some complications restoring it.
Profiling stuff (mostly in *.s):
o Changes to kern/subr_mcount.c, gcc and gprof are not supplied yet.
o All interesting labels `foo' are renamed `_foo' and all
uninteresting labels `_bar' are renamed `bar'. A small change
to gprof allows ignoring labels not starting with underscores.
o MCOUNT_LABEL() is to provide names for counters for times spent
in exception handlers.
o FAKE_MCOUNT() is a version of MCOUNT() suitable for exception
handlers. Its arg is the pc where the exception occurred. The
new mcount() pretends that this was a call from that pc to a
suitable MCOUNT_LABEL().
o MEXITCOUNT is to turn off any timer started by MCOUNT().
/usr/src/sys/i386/i386/exception.s:
o The non-BDB BPTTRAP() macros were doing a sti even when interrupts
were disabled when the trap occurred. The sti (fixed) sti is
actually a no-op unless you have my changes to machdep.c that make
the debugger trap gates interrupt gates, but fixing that would
make the ifdefs messier. ddb seems to be unharmed by both
interrupts always disabled and always enabled (I had the branch in
the fix back to front for some time :-().
o There is no known pushal bug.
o tf_err can be left as garbage for syscalls.
/usr/src/sys/i386/i386/locore.s:
o Fix and update BDE_DEBUGGER support.
o ENTRY(btext) before initialization was dangerous.
o Warm boot shot was longer than intended.
/usr/src/sys/i386/i386/machdep.c:
o DON'T APPLY ALL OF THIS DIFF. It's what I'm using, but may require
other changes.
Use the following:
o Remove aston() and setsoftclock().
Maybe use the following:
o No netisr.h.
o Spelling fix.
o Delay to read the Rebooting message.
o Fix for vm system unmapping a reduced area of memory
after bounds_check_with_label() reduces the size of
a physical i/o for a partition boundary. A similar
fix is required in kern_physio.c.
o Correct use of __CONCAT. It never worked here for non-
ANSI cpp's. Is it time to drop support for non-ANSI?
o gdt_segs init. 0xffffffffUL is bogus because ssd_limit
is not 32 bits. The replacement may have the same
value :-), but is more natural.
o physmem was one page too low. Confusing variable names.
Don't use the following:
o Better numbers of buffers. Each 8K page requires up to
16 buffer headers. On my system, this results in 5576
buffers containing [up to] 2854912 bytes of memory.
The usual allocation of about 384 buffers only holds
192K of disk if you use it on an fs with a block size
of 512.
o gdt changes for bdb.
o *TGT -> *IDT changes for bdb.
o #ifdefed changes for bdb.
/usr/src/sys/i386/i386/microtime.s:
o Use the correct asm macros. I think asm.h was copied from Mach
just for microtime and isn't used now. It certainly doesn't
belong in <sys>. Various macros are also duplicated in
sys/i386/boot.h and libc/i386/*.h.
o Don't switch to and from the IRR; it is guaranteed to be selected
(default after ICU init and explicitly selected in isa.c too, and
never changed until the old microtime clobbered it).
/usr/src/sys/i386/i386/support.s:
o Non-essential changes (none related to spls or profiling).
o Removed slow loads of %gs again. The LDT support may require
not relying on %gs, but loading it is not the way to fix it!
Some places (copyin ...) forgot to load it. Loading it clobbers
the user %gs. trap() still loads it after certain types of
faults so that fuword() etc can rely on it without loading it
explicitly. Exception handlers don't restore it. If we want
to preserve the user %gs, then the fastest method is to not
touch it except for context switches. Comparing with
VM_MAXUSER_ADDRESS and branching takes only 2 or 4 cycles on
a 486, while loading %gs takes 9 cycles and using it takes
another.
o Fixed a signed branch to unsigned.
/usr/src/sys/i386/i386/swtch.s:
o Move spl0() outside of idle loop.
o Remove cli/sti from idle loop. sw1 does a cli, and in the
unlikely event of an interrupt occurring and whichqs becoming
zero, sw1 will just jump back to _idle.
o There's no spl0() function in asm any more, so use splz().
o swtch() doesn't need to be superaligned, at least with the
new mcounting.
o Fixed a signed branch to unsigned.
o Removed astoff().
/usr/src/sys/i386/i386/trap.c:
o The decentralized extern decls were inconsistent, of course.
o Fixed typo MATH_EMULTATE in comments. */
o Removed unused variables.
o Old netmask is now impmask; print it instead. Perhaps we
should print some of the new masks.
o BTW, trap() should not print anything for normal debugger
traps.
/usr/src/sys/i386/include/asmacros.h:
o DON'T APPLY ALL OF THIS DIFF. Just use some of the null macros
as necessary.
/usr/src/sys/i386/include/cpu.h:
o CLKF_BASEPRI() changes since cpl == SWI_AST_MASK is now normal
while the kernel is running.
o Don't use var++ to set boolean variables. It fails after a mere
4G times :-) and is slower than storing a constant on [3-4]86s.
/usr/src/sys/i386/include/cpufunc.h:
o DON'T APPLY ALL OF THIS DIFF. You need mainly the include of
<machine/ipl.h>. Unfortunately, <machine/ipl.h> is needed by
almost everything for the inlines.
/usr/src/sys/i386/include/ipl.h:
o New file. Defines spl inlines and SWI macros and declares most
variables related to hard and soft interrupt masks.
/usr/src/sys/i386/isa/icu.h:
o Moved definitions to <machine/ipl.h>
/usr/src/sys/i386/isa/icu.s:
o Software interrupts (SWIs) and delayed hardware interrupts (HWIs)
are now handled uniformally, and dispatching them from splx() is
more like dispatching them from _doreti. The dispatcher is
essentially *(handler[ffs(ipending & ~cpl)]().
o More care (not quite enough) is taken to avoid unbounded nesting
of interrupts.
o The interface to softclock() is changed so that a trap frame is
not required.
o Fast interrupt handlers are now handled more uniformally.
Configuration is still too early (new handlers would require
bits in <machine/ipl.h> and functions to vector.s).
o splnnn() and splx() are no longer here; they are inline functions
(could be macros for other compilers). splz() is the nontrivial
part of the old splx().
/usr/src/sys/i386/isa/ipl.h
o New file. Supposed to have only bus-dependent stuff. Perhaps
the h/w masks should be declared here.
/usr/src/sys/i386/isa/isa.c:
o DON'T APPLY ALL OF THIS DIFF. You need only things involving
*mask and *MASK and comments about them. netmask is now a pure
software mask. It works like the softclock mask.
/usr/src/sys/i386/isa/vector.s:
o Reorganize AUTO_EOI* macros.
o Option FAST_INTR_HANDLER_USERS_ES for people who don't trust
fastintr handlers.
o fastintr handlers need to metamorphose into ordinary interrupt
handlers if their SWI bit has become set. Previously, sio had
unintended latency for handling output completions and input
of SLIP framing characters because this was not done.
/usr/src/sys/net/netisr.h:
o The machine-dependent stuff is now imported from <machine/ipl.h>.
/usr/src/sys/sys/systm.h
o DON'T APPLY ALL OF THIS DIFF. You need mainly the different
splx() prototype. The spl*() prototypes are duplicated as
inlines in <machine/ipl.h> but they need to be duplicated here
in case there are no inlines. I sent systm.h and cpufunc.h
to Garrett. We agree that spl0 should be replaced by splnone
and not the other way around like I've done.
/usr/src/sys/kern/kern_clock.c
o splsoftclock() now lowers cpl so the direct call to softclock()
works as intended.
o softclock() interface changed to avoid passing the whole frame
(some machines may need another change for profile_tick()).
o profiling renamed _profiling to avoid ANSI namespace pollution.
(I had to improve the mcount() interface and may as well fix it.)
The GUPROF variant doesn't actually reference profiling here,
but the 'U' in GUPROF should mean to select the microtimer
mcount() and not change the interface.
Example:
Application use port cua01
Getty open ttyd1 (allocates rawq,outq,etc) and waits while application
done
Application quits, sioclose issued, ttyfree issued (getty calls revoke)
Getty awakes and goes to panic into initrb (NULL rawq)
now HUPCL set only in bidir case for callin lines
(this prevents set HUPCL on mouse)
comhardclose:
in addition to HUPCL case now DTR dropped for bidir case
if line was active in and no carrier present now.
(this prevents DTR sleep on mouse)
This inetrface should be used from now on.
pseudo device pty xx still keeps its meaning: a maximum of
xx ptys is allowed.
A ringbuffer is now 2040 bytes long, per Garrett Wollman's request.
The changes are inspired by the way NetBSD did it (thanks for that!),
though I made it slihghtly different, including the interface so
at least 75% of the allocated space is deallocated when the tty is
closed.
Note further that it is easy to modify the ringbuffer length runtime.
This will have to wait untill some later date...
-Guido
netmask or impmask.
2) Fixes from Bruce:
o Changed name of schedsoftcom() to setsofttty() to match
setsoftclock()
o Bool_t isn't used.
o tx_fifo_size is 1 for chips without fifos, 16 for 16550's, to
help to output more efficiently for 16550's (LSR_TXRDY means
that the fifo is empty, not that it has space for one char).
o Changed name of softsio1() to siopoll() and merged compoll()
into siopoll().
o The probe forgot to clear com_mcr after it failed. This is
harmful for 4 single serial ports on 2 interrupts. It makes
partial misconfigurations worse.
o Don't bother initializing static variables that are 0 (bidir
stuff).
o Only initialize t_oflag to TTYDEF_OFLAG if unit == COMCONSOLE,
not if COMCONSOLE is defined.
o Don't call siointr() from comparam() if there is no output in
progress. For the call from sioopen(), there's no output in
progress, and siointr() often saw silo overflows for stale
input because it was called before sioopen() discarded the
input.
o Let ttselect() do the work for select(), so that the fixes for
ttselect() don't have to be duplicated in zillions of drivers.
file override to disable fifo on 16550s:
I bought a board with two 16550's, but one of those ports has a mouse
on it. The sio driver always enables the fifo, which is a bad thing
for mice and X. The mouse is jerky and hard to use. The simple thing
is be to treat one of the ports as a non-fifo'ed UART, and I use the
flags option in my config file.
So, my config file has:
device sio0 at isa? port "IO_COM1" tty irq 4 flags 0x2 vector siointr
device sio1 at isa? port "IO_COM2" tty irq 3 vector siointr
(patch deleted)
Choose older MULTIPORT version, because lastest bde version
not worked.
Don't force HUPCL for bidirectional case.
From bde:
Use bit (1 << (16 + 4)) in schedsoftcom() to avoid clash with
non-serial h/w on IRQ4.
Allow FIFO_TRIGGER in config.
Clear com->mcr_image when clearing mcr for init of 4port. The
usual value MCR_IENABLE should have broken 4ports unless
something happened to clear it later.
Turn off interrupts as well as DTR after an error waiting for
carrier (bidir dialin case).
Drain fifo more carefully.
Don't hang up if debugging.
Rearrange siointr() -> siointr1() for multiport case for speed,
lower latency and clarity.
Use suser() to check perms.
Provide missing splx() after failed perms checks.
c_ispeed == 0 means c_ispeed = c_ospeed (POSIX).
Set parameters (except speed) for c_ospeed == 0 as well as
hanging up.
Better initialization for console (fifo stuff...).
Misc. cleanups.
Fix dead hang if modem power is off.
added to probe.
2) Force CLOCAL=on for outgoing ports and CLOCAL=off for
incoming ports into open in bidirectional case.
3) Add DELAY after writing to com_ier for fifo drain into probe.
That is because TIOCMGET was broken. Yes...this is known for some time
and no, we (Bruce and me) never posted it. Why? Simply because we choose
to post fixes when we fixed most of the bugs.
Anyway..now that the slip problems are coming, here is a fix for
correct TIOCMGET behaviour.
-Guido
Note: this should be tested first (Rich?). Tested by rgrimes
