oneill@bass.bu.edu (Brian V O'Neill) (12/19/90)
This may have gone around before, but I have a problem building the color server on a DEC VAX under Ultrix 4.X. When it attempts to build Xqdss, it fails in qdss_io.c, on line 676 with "g undefined". An inspection of the line shows it is an ioctl call: ioctl(fd_qdss, SG_VIDEOON, &Sg); It appears to be failing in the last parameter, but I don't see why it is ignoring the S. i also cannot find SG_VIDEOON defined anywhere. Likewise, it fails on line 683, which is the same call with SG_VIDEOOFF. As near as I can tell this is for the screen saver. Both lines are the "else" part of an if statement, whose condition is "(!Vaxstar)". Is it safe to assume that if I'm not compiling on a Vaxstar (or VS2000), I could temporarily remove these lines? Are there any other solutions? -- ============================================================================ Brian O'Neill - Local Internet Access Account Internet: oneill@bu-pub.bu.edu UUCP : ...!bu.edu!bu-pub!oneill
lriffe@triton.unm.edu (Larry Riffe II) (12/20/90)
Brian,
There is indeed a problem with the 2 lines you mention, but
the problem is not with the third variable, its with the second.
It appears that this is not caused so much by a bug but more
by changes DEC made to their OS that MIT doesn't know about.
Follow along and I'll explain:
In mit/server/ddx/dec/qdss/qdss_io.c we have the following lines:
if (on != SCREEN_SAVER_ON)
{
lastEventTime = GetTimeInMillis();
if (!Vaxstar)
*(short *) Qdss.memcsr = UNBLANK | SYNC_ON;
else
ioctl(fd_qdss, SG_VIDEOON, &Sg); /* <= ERRORS HERE */
}
else
{
if (!Vaxstar)
*(short *) Qdss.memcsr = SYNC_ON;
else
ioctl(fd_qdss, SG_VIDEOOFF, &Sg); /* <= ERRORS HERE */
}
With the errors you mentioned occurring on the lines that are
pointed to.
In mit/server/ddx/dec/qdss/libtl/tl.h we have:
#ifdef __STDC__
#define SG_MAPDEVICE _IOR('g', 9, struct sgmap) /* map device to user */
#define SG_VIDEOON _IO('g',23) /* turn on the video */
#define SG_VIDEOOFF _IO('g',24) /* turn off the video */
#define SG_CURSORON _IO('g',25) /* turn on the cursor */
#define SG_CURSOROFF _IO('g',26) /* turn off the cursor */
#else
#define SG_MAPDEVICE _IOR(g, 9, struct sgmap) /* map device to user */
#define SG_VIDEOON _IO(g,23) /* turn on the video */
#define SG_VIDEOOFF _IO(g,24) /* turn off the video */
#define SG_CURSORON _IO(g,25) /* turn on the cursor */
#define SG_CURSOROFF _IO(g,26) /* turn off the cursor */
#endif
And this is where the problem happens! The variable __STDC__
is supposed to be defined as 1 if the C compiler is ANSI C
compliant! DEC's is not and thus this defines the second set
of variables instead of the first set.
Now _IO is defined in /usr/include/sys/ioctl.h! And DEC decided
to change this definition between Ultrix 3.1 and 4.0. Thus
causing the problem your having.
Ultrix 3.1 /usr/include/sys/ioctl.h:
#define _IO(x,y) (int)(IOC_VOID|('x'<<8)|y)
And Ultrix 4.0 /usr/include/sys/ioctl.h:
#define _IO(x,y) (int)(_IOC_VOID|(x<<8)|y)
If you notice, there are no ' around the x variable. So, that
means we have to define our original variables (the ones from
/mit/server/ddx/dec/qdss/libtl/tl.h) as if we are using an ANSI
C compliant compiler. But, since we are not using an ANSI C
compliant compiler (I've heard that DEC is working on this,
but so far, their C compiler is not) we get an error and the
color X server doesn't build for a VAX arch. machine.
So, the question is how to fix this. I've come up with two
methods, the first I don't know how to implement and the second
which is a hack but does happen to work.
The first method involves modifying the imakefile so that it
will compile all of the source code in mit/server/ddx/dec/qdss
with the option -DOSMajorVersion=???. Then change the #ifdef
in mit/server/ddx/dec/qdss/libtl/tl.h to look like:
#if ( (__STDC__) || ( OSMajorVersion > 3 ) )
The only problem with this, is that I don't know how to modify
the imakefile to compile everything with the option I specified
above! Is there anybody out there who can tell me what needs
to be changed to do this?
The second method is a hack, I don't like it, but it's quick
and it works. The first thing is to make a backup copy of
mit/server/ddx/dec/qdss/libtl/tl.h. Then edit the copy in
your source tree so that there is no longer a #ifdef and you
only define the correct variables. i.e.
#define SG_MAPDEVICE _IOR('g', 9, struct sgmap) /* map device to user */
#define SG_VIDEOON _IO('g',23) /* turn on the video */
#define SG_VIDEOOFF _IO('g',24) /* turn off the video */
#define SG_CURSORON _IO('g',25) /* turn on the cursor */
#define SG_CURSOROFF _IO('g',26) /* turn off the cursor */
Make sure you keep a backup copy of this file so that you can
put it back in place after you have compiled the server code.
Hope this helps,
Larry G. Riffe II
lriffe@triton.unm.edu
lriffe@triton.cirt.unm.edu