From: Erik Berglund <erik2 DOT berglund AT telia DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: GPF with system() and clock int.
Lines: 68
Message-ID: <KyAe5.2195$652.79573@newsc.telia.net>
Date: Sun, 23 Jul 2000 11:21:14 GMT
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To: djgpp AT delorie DOT com
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"Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il> wrote:
> 
> > (with the clock tick frequency at 16x 18.2 Hz)
> 
> This clock speedup is actually not very nice on your part: what if
> some of the drivers you load catch the timer tick, and cannot keep up
> with the 16-fold rate increase?
> 
> What CPU is that, btw?

It is a Pentium Pro 200 MHz. The clock speedup is only for testing
of this error.
 
> > Anyways, my 16-bit Turbo
> > Pascal TSR does the same job, and it seems to work well
> > together with gcc.
> 
> There's overhead associated with hardware interrupts in PM, as you
> well know.

Do you mean that a 16-bit TSR runs slower because of overhead in
the foreground gcc program?

In order to trig the error more easily, I have modified tu20.c
so the clock tick frequency is 256x 18.2 Hz (normally I would
use 1x 18.2 Hz). I also modified CONFIG.SYS and AUTOEXEC.BAT
to much shorter versions:

-- CONFIG.SYS --
DEVICE=C:\DOS\HIMEM.SYS /TESTMEM:OFF
FILES=40
-- End of CONFIG.SYS --

-- AUTOEXEC.BAT --
PATH C:\BIN;C:\DOS;C:\DJGPP\BIN
SET DJGPP=C:\DJGPP\DJGPP.ENV
SET TMP=C:\TMP
SET TEMP=C:\TMP
SMARTDRV
CD \USERS\EB\DSP
-- End of AUTOEXEC.BAT --

-- Error message --
General Protection Fault in RMCB at eip=aa35; flags=3046
eax=00013000 ebx=000020c7 ecx=000007fc edx=000007c2 esi=00025f18 edi=00002354
ebp=0005091d esp=00002578 cs=400 ds=0 es=0 fs=0 gs=0 ss=20 error=0028
-- End of error message --

If SMARTDRV is removed, I get (this message was copied manually from
the screen because the computer locked up, so it is approximate):
-- Error message --
Invalid TSS in RMCB at eip=e90; flags=2
eax=00000002 ebx=00000000 ecx=00000020 edx=00000000 esi=0001ac58 edi=0000226c
ebp=00000000 esp=00002682 cs=18 ds=38 es=db9 fs=0 gs=0 ss=20 error=0db8
Invalid TSS in RMCB at eip=3db0; flags=2
eax=00000002 ebx=00000000 ecx=00000020 edx=00000000 esi=0001ac58 edi=0000226c
ebp=00000000 esp=000013c8 cs=2b ds=38 es=db9 fs=0 gs=0 ss=33 error=0db8
Invalid TSS in RMCB at eip=3db0; flags=2
eax=00000002 ebx=00000000 ecx=00000020 edx=00000000 esi=0001ac58 edi=0000226c
ebp=00000000 esp=000013c8 cs=2b ds=38 es=db9 fs=0 gs=0 ss=33 error=0db8
-- End of error message --

--

Erik Berglund
erik2 DOT berglund AT telia DOT com