Matrox Mystique G200 Manuel d'utilisateur télécharger pdf (Page 18)

The next important item about the video hardware is the base address of the video memory. That is given by

the (scrmem) parameter as a hexadecimal number with an 0x prefix. You will need to find this out from the

documentation that comes with your external video hardware.

The next paramter (scrlen) tells the kernel about the size of the video memory. If it's missing, this is calculated

from the (xres), and (depth) parameters. It's not useful to write a value here these days anyway. To leave this

empty, give two consecutive semicolons if you need to give the (vgabase) parameter, otherwise, just leave it.

The (vgabase) parameter is optional. If it isn't given, the kernel can't read/write any colour registers of the

video hardware, and thus you have to set up the appropriate colours before you boot Linux. But if your card is

VGA compatible, you can give it the address where it can locate the VGA register set so it can change the

colour lookup tables. This information can be found in your external video hardware documentation. To make

this clear, (vgabase) is the base address, i.e a 4k aligned address. For reading/writing the colour registers, the

kernel uses the address range between (vgabase) + 0x3c7 and (vgabase) + 0x3c9. This parameter is given in

hexadecimal and must have a 0x prefix, just like (scrmem). (colw) is only meaningful, if the (vgabase)

parameter is specified. It tells the kernel how wide each of the colour register is, i.e the number of bits per

single colour (red/green/blue). Default is usually 6 bits, but it is also common to specify 8 bits.

(xres_virtual) is only required for the ProMST/ET4000 cards where the physical linelength differs from the

visible length. With ProMST, you need to supply 2048, whilst for ET4000, it depends on the initialisation of

the video board.

5.2. Amiga platforms

This section describes the options for Amigas, which are quite similar to those of the Atari platform

5.2.1. What modes are available?

This depends on the chipset used in the Amiga. There are three main ones; OCS, ECS and AGA which all

uses the colour frame buffers.

NTSC modes•

ntsc - 640x200♦

ntsc-lace - 640x400♦

•

PAL modes•

pal - 640x256♦

pal-lace - 640x512♦

•

ECS modes - 2 bit colours on ECS chipsets, 8 bit colours on AGA chipsets only•

multiscan - 640x480♦

multiscan-lace - 640x960♦

euro36 - 640x200♦

euro36-lace - 640x400♦

euro72 - 640x480♦

euro72-lace - 640x800♦

super72 - 800x300♦

super72-lace - 800x400♦

dblntsc - 640x200♦

dblpal - 640x256♦

dblntsc-ff - 640x400♦

dblntsc-lace - 640x800♦

•

Framebuffer HOWTO

5. Using framebuffer devices on m68k platforms 15

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