I have several computers equipped with a S3 ViRGE/DX or /GX (rev 01)
lspci says :
        0000:00:09.0 Class 0300: 5333:8a01 (rev 01)
and VESA BIOS says :
        S3 Incorporated. 86C375/86C385

I cannot make the Xorg server with s3virge driver work with those cards.

I always get a garbled screen, where one recognizes the typical X-pattern,
but :
    - there are full-height vertical magenta lines every 8 pixel on the
        3/4 of the width of the screen
    - with hw_cursor, the cursor drags a small white vertical box with him
    - with sw_cursor, the cursor erases the screen in a magenta/black mix
    - only with sw_cursor and ShadowFB can I have a good cursor, but
        the vertical magenta lines are still there
    - when I switch off the graphical mode back to the text mode, the text
        screen is garbled, with the text of the first columns repeating
        itself after column 64, and small colored stripes one pixel high
        and one character wide flickering in the column in the middle.

I am willing to compile and test any test version you would provide me
or try to fix the problem myself, if I could have access to the data sheets
of those chips.

Could you send me those data sheets, or point me to a site where they would be
available ?

IIRC, the very old standalone s3_virge driver managed to display a correct
X screen, but switching back to the text mode was garbled exactly as it is now.

Thanks for reading so far.

Philippe