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VGA hardware provides many different graphics and data access modes, each with different capabilities and limitations. VGA vt(4) graphics mode operates on blocks of pixels at a time. When a given pixel block contains only two colours the vt_vga driver uses write mode 3. When the block contains more than two colours it uses write mode 0. This is done because two-colour write mode 3 is much more efficient. In practice write mode 3 is used most of the time, as there is often a single foreground colour and single background colour across the entire console. One common exception requiring the use of mode 0 is when the mouse cursor is drawn over a background other than black, as we need black and white for the cursor in addition to the background colour. VGA's default 16-colour palette provides the same set of colours as the system console, but in a different order. Previously we configured a non-default VGA palette that had the same colours at the same indexes. However, this caused anything drawn before the kernel started (drawn by the loader, for instance) to change colours once the kernel configured the new, non-default palette. In |
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colors | ||
font | ||
hw | ||
logo | ||
vt_buf.c | ||
vt_consolectl.c | ||
vt_core.c | ||
vt_cpulogos.c | ||
vt_font.c | ||
vt_sysmouse.c | ||
vt.h |