can not start monitor

Rainer Bärs rainer.bars at
Thu Oct 2 01:14:58 EDT 1997

>> Subject: can not start monitor
>> I just recompiled grass for my DEC Alphastation and for my SGI INDY. After
>> getting the usual (?) compilation errors, I finally got everything up and
>> running. Or so I thought!
>> When I say 'd.mon start=x0' to my Alphastation it says:
>> Graphics driver [x0] started
>> can't read index!
>> ERROR eof from graphics driver.
>> Problem selecting x0. Will try once more
>> Please start graphics monitor <x0>.
>> Error - Graphics monitor <x0> not running!


>The problem turned out to be that to process the fonts for the graphics
>they were reading from a file a certain number of bytes. The calculation of
>this number of bytes was based on the size of a pointer (8 for 64 bit systems)
>when in reality, the number of bytes available for reading was based on 4 (the
>size of pointers on 32 bit systems). It actually has nothing to do with the
>size of pointers, thus the calculation was too large and the read command was
>trying to read more bytes than were available. The problem was fixed by
>changing line 43 of the file $GIS/src/display/devices/XDRIVER/lib/font.c
>to the
>	size = nchars * 4;

This did it, now it works OK. Thanks Justin, and everyone else who
responded to my original message.

This probably is an old thought, and should be on grass-p, but
these 32- and 64-bit (and 128-bit and...) are going to cause us a lot
more trouble in the future, if no systematic approach is taken.

Best, Rainer

e-mail:         rainer.bars at
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