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Clarifications requested by Robert. EGA text part.
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@@ -477,10 +477,7 @@ start running the operating system.
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All of the graphics fields are enabled by flag bit 2. They specify the
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preferred graphics mode. Note that that is only a @emph{recommended}
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mode by the OS image. If the mode exists, the boot loader should set
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it, when the user doesn't specify a mode explicitly. Otherwise, the
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boot loader should fall back to a similar mode, if available. Boot loader
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may also choose another mode if it sees fit.
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mode by the OS image. Boot loader may also choose another mode if it sees fit.
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The meaning of each is as follows:
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@@ -947,7 +944,7 @@ if they were @sc{vbe} modes.
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If bit 12 in the @samp{flags} is set, the @sc{Framebuffer} table is available.
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The field @samp{framebuffer_addr} contains framebuffer physical address. This field is 64-bit wide but bootloader @dfn{should} set it under 4GiB if possible for compatibility with payloads which aren't aware of PAE or amd64. The field @samp{framebuffer_pitch} contains pitch in bytes. The fields @samp{framebuffer_width}, @samp{framebuffer_height} contain framebuffer dimensions in pixels. The field @samp{framebuffer_bpp} contains number of bits per pixel. If @samp{framebuffer_type} is set to 0 it means indexed color. In this case color_info is defined as following:
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The field @samp{framebuffer_addr} contains framebuffer physical address. This field is 64-bit wide but bootloader @dfn{should} set it under 4GiB if possible for compatibility with payloads which aren't aware of PAE or amd64. The field @samp{framebuffer_pitch} contains pitch in bytes. The fields @samp{framebuffer_width}, @samp{framebuffer_height} contain framebuffer dimensions in pixels. The field @samp{framebuffer_bpp} contains number of bits per pixel. If @samp{framebuffer_type} is set to 0 it means indexed color. In this case color_info is defined as follows:
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@example
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@group
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+----------------------------------+
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@@ -956,7 +953,7 @@ The field @samp{framebuffer_addr} contains framebuffer physical address. This fi
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+----------------------------------+
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@end group
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@end example
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@samp{framebuffer_palette_addr} contains address of array of @samp{framebuffer_palette_num_colors} following structures:
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@samp{framebuffer_palette_addr} contains address of palette. Palette is an array of colour descriptors. Each colour descriptor has following structure:
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@example
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@group
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+-------------+
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@@ -966,7 +963,7 @@ The field @samp{framebuffer_addr} contains framebuffer physical address. This fi
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+-------------+
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@end group
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@end example
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If @samp{framebuffer_type} is set to 1 it direct RGB color. Then color_type is defined as following:
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If @samp{framebuffer_type} is set to 1 it means direct RGB color. Then color_type is defined as follows:
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@example
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@group
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@@ -980,6 +977,8 @@ If @samp{framebuffer_type} is set to 1 it direct RGB color. Then color_type is d
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+----------------------------------+
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@end group
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@end example
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If @samp{framebuffer_type} is set to 2 it means EGA text. In this case @samp{framebuffer_width} and @samp{framebuffer_height} are expressed in characters and not in pixels. @samp{framebuffer_bpp} is equal 16 (16 bits per character) and @samp{framebuffer_pitch} is expressed in bytes per text line.
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All further values of @samp{framebuffer_type} are reserved for future expansion
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@node Examples
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