What do you know, something I know about. Actually, I don't know
about VESA, but I know about graphics modes.
> OKUJI Yoshinori <[EMAIL PROTECTED]> writes:
>
...
> 32 | required_width | (present if flags[2] is set)
> 36 | required_height | (present if flags[2] is set)
> 40 | required_depth | (present if flags[2] is set)
>
If you have space you should probably add a pitch value. The
width is the number of dots on the screen on one line. The pitch
is the number of bytes or pixels you need to skip to get to the
next line. Graphics cards often place a single screen line in
one or more cache lines in the ASIC. If the width is not an
integral multiple of the ASIC cache line size there has to be some
padding.
I don't know if this is an issue with VESA or not, as I have never
looked at the VESA spec. However, I know that the BIOS of the
graphics card we make returns the pitch, so I assume it is important
at boot time.
Finally, if you ever intend to support more than 8BPP graphics modes,
you should make sure to document whether the pitch and width is in
bytes or pixels. This sounds like an obvious point, but in the OpenGL
and D3D drivers I have worked on, it has wasted days and days of
people's time.
