Indeed. If the VESA BIOS does not subtract the MMIO area before reporting
the framebuffer size then it is IMHO broken.
To go off at a tangent...
In fact, the size reported by VESA has to be a multiple of 64K so it is
rounded down. There should be no MMIO area in the framebuffer reported
by VESA. Unfortunately, though, if you believe both the framebuffer size
and the maximum number of lines as reported by the BIOS then your program
might break (example: on Neomagic NM2093 system at 1024 bytes per line the
BIOS reports the maximum number of lines as 1117 but the BIOS claims the
framebuffer is only 1088K - so you mmap 1088K and try to use 1117K and your
program segfaults. I guess there is actually 1152K installed on the board
but it uses the rest of the memory for its own purposes).
imc
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