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| Framebuffer HOWTO英文 |
热 ★★★★ |
| Framebuffer HOWTO英文 |
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作者：4Lzx.com 文章来源：bbs.4Lzx.com 点击数： 更新时间：2005-9-4 18:51:58  |
able with the video=xxxparameter:
* inverse - inverts the display so that the background/foregroundcolours are reversed. Normally the background is black, but with thissuboption, it gets sets to white.
* font - sets the font to use in text modes. Currently you canonly select VGA8x8, VGA8x16, PEARL8x8. The default is touse the VGA8x8 only if the vertical size of the display is less than400 pixels, otherwise it defaults to VGA8x16.
* internal - a very interesting option. See the next section forinformation.
* external - as above.
* monitorcap - describes the capabilities for multisyncs. DON'Tuse with a fixed sync monitor!
6.3 Using the internal suboption on Atari m68k platforms
Syntax: internal:(xres);(yres)[;(xres_max);(yres_max);(offset)]
This option specifies the capabilities of some extended internal videohardware, i.e OverScan modes. (xres) and (yres) gives theextended dimensions of the screen.
If your OverScan mode needs a black border, you'll need to write the lastthree arguments of the internal: suboption. (xres_max) is themaximum line length that the hardware allows, (yres_max) is themaximum number of lines, and (offset) is the offset of the visiblepart of the screen memory to its physical start, in bytes.
Often extended internal video hardware has to be activated, for this youwill need the "switches=*" options. [Note: Author would like extrainformation on this, please. The m68k documentation in the kernel isn'tclear enough on this point, and he doesn't have an Atari! Examples wouldbe helpful too]
6.4 Using the external suboption on Atari m68k platforms
Syntax:external:(xres);(yres);(depth);(org);(scrmem)[;(scrlen)[;(vgabase)[;(colw)[;(coltype)[;(xres_virtual)]]]]]
This is quite complicated, so this document will attempt to explain asclearly as possible, but the Author would appreciate if someone would givethis a look over and see that he hasn't fscked something up! :o)
This suboption specifies that you have an external video hardware (mostlikely a graphic board), and how to use it with Linux. The kernel isbasically limited to what it knows of the internal video hardware, so youhave to supply the parameters it needs in order to be able to use externalvideo hardware. There are two limitations; you must switch to that modebefore booting, and once booted, you can't change modes.
The first three parameters are obvious; gives the dimensions of the screenas pixel height, width and depth. The depth supplied should be the numberof colours is 2^n that of the number of planes required. For example, ifyou desire to use a 256 colour display, then you need to give 8 as thedepth. This depends on the external graphic hardware, though so you willbe limited by what the hardware can do.
Following from this, you also need to tell the kernel how the video memoryis organised - supply a letter as the (org) parameter
* n - use normal planes, i.e one whole plane after another
* i - use interleaved planes, i.e. 16 bits of the first plane,then the 16 bits of the next plane and so on. Only built-in Atari videomodes uses this - and there are no graphic card that supports this mode.
* p - use packed pixels, i.e consecutive bits stands for allplanes for a pixel. This is the most common mode for 256 colour displayson graphic cards.
* t - use true colour, i.e this is actually packed pixels, butdoes not require a colour lookup table like what other packed pixel modesuses. These modes are normally 24 bit displays - gives you 16.8 millioncolours.
However, for monochrome modes, the (org) parameter has adifferent meaning
* n - use normal colours, i.e 0=white, 1=black
* i - use inverted colours, i.e. 0=black, 1=white
The next important item about the video hardware is the base address ofthe video memory. That is given by the (scrmem) parameter as ahexadecimal number with an 0x prefix. You will need to find this outfrom the documentation that comes with your external video hardware.
The next paramter (scrlen) tells the kernel about the size of thevideo memory. If it's missing, this is calculated from the (xres),(yres) and (depth) parameters. It's not useful to write a valuehere these days anyway. To leave this empty, give two consecutivesemicolons if you need to give the (vgabase) parameter, otherwise,just leave it.
The (vgabase) parameter is optional. If it isn't given, the kernelcan't read/write any colour registers of the video hardware, and thus youhave to set up the appropriate colours before you boot Linux. But if yourcard is VGA compatible, you can give it the address where it can locatethe VGA register set so it can change the colour lookup tables. Thisinformation can be found in your external video hardware documentation. Tomake this clear, (vgabase) is the base address, i.e a 4kaligned address. For reading/writing the colour registers, the kernel usesthe address range between (vgabase) + 0x3c7 and (vgabase) +0x3c9. This parameter is given in hexadecimal and must have a 0xprefix, just like (scrmem).
(colw) is only meaningful, if the (vgabase) parameter isspecified. 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 isusually 6 bits, but it is also common to specify 8 bits.
(coltype) is used with the (vgabase) parameter, it tells thekernel about the colour register model of your graphic board. Currentlythe types supported are vga and mv300. vga is the default.
(xres_virtual) is only required for the ProMST/ET4000 cards where thephysical linelength differs from the visible length. With ProMST, you needto supply 2048, whilst for ET4000, it depends on the initialisation of thevideo board.
7. Using framebuffer devices on Amiga m68k platforms
This section describes the options for Amigas, which are quite similiar tothat for the Atari m68k platforms.
7.1 What modes are available for Amiga m68k platforms?
This depends on the chipset used in the Amiga. There are three main ones;OCS, ECS and AGA which all uses the colour frame buffer device.
* NTSC modes
o ntsc - 640x200
o ntsc-lace - 640x400
* PAL modes
o pal - 640x256
o pal-lace - 640x512
* ECS modes - 2 bit colours on ECS, 8 bit colours on AGA chipsetsonly.
o multiscan - 640x480
o multiscan-lace - 640x960
o euro36 - 640x200
o euro36-lace - 640x400
o euro72 - 640x400
o euro72-lace - 640x800
o super72 - 800x300
o super72-lace - 800x600
o dblntsc - 640x200
o dblpal - 640x256
o dblntsc-ff - 640x400
o dblntsc-lace - 640x800
o dblpal-ff - 640x512
o dblpal-lace - 640x1024
* VGA modes - 2 bit colours on ECS, 8 bit colours on AGA chipsetsonly.
o vga - 640x480
o vga70 - 640x400
7.2 Additional suboptions on Amiga m68k platforms
These are similar to the Atari m68k suboptions. They are:
* depth - specifies the pixel bit depth.
* inverse - does the same thing as the Atari suboption.
* font - does the same thing as the Atari suboption, although thePEARL8x8 font is used instead of VGA8x8 font, if the displaysize is less than 400 pixel wide.
* monitorcap - specifies the capabilities of the multisyncmonitor. Do not use with fixed sync monitors.
7.3 Supported Amiga graphic expansion boards
* Phase5 CyberVision 64 (S3 Trio64 chipset)
* Phase5 CyverVision 64-3D (S3 ViRGE chipset)
* MacroSystems RetinaZ3 (NCR 77C32BLT chipset)
* Helfrich Piccolo, SD64, GVP ECS Spectrum, Village Tronic PicassoIIII+ and IV/ (Cirrus Logic GD542x/543x)
8. Using framebuffer devices on Macintosh m68k platforms
Currently, the framebuffer device implemented only supports the modeselected in MacOS before booting into Linux, also supports 1, 2, 4 and 8bit colours modes.
Framebuffer suboptions are selected using the following syntax
video=macfb:<font>:<inverse>
You can select fonts such as VGA8x8, VGA8x16 and 6x11 etc. The inverseoption allows you to use reverse video.
9. Using framebuffer devices on PowerPC platforms
The author would love to receive information on the use of framebuffers onthis platform.
10. Using framebuffer devices on Alpha platforms
10.1 What modes are available to me?
So far, there is only the TGA PCI card - which only does 80x30 with aresolution of 640x480 at either 8 bits or 24/32 bits.
10.2 Which graphic cards can work with the frambuffer device?
This lists all the graphic cards that are known to work:
* DEC TGA PCI (DEC21030) - 640x480 @ 8 bit or 24/32 bit versions
11. Using framebuffer devices on SPARC platforms
11.1 Which graphic cards can work with the framebuffer device?
This lists all the graphic cards available:
* MG1/MG2 - SBus or integrated on Sun3 - max. 1600x1280 @ mono (BWtwo)
* CGthree - Similar to MG1/MG2 but supports colour - max resolution ?
* GX - SBus - max. 1152x900 @ 8bit (CGsix)
* TurboGX - SBus - max. 1152x900 @ 8 bit (CGsix)
* SX - SS10/SS20 only - max. 1280x1024 @ 24 bit - (CGfourteen)
* ZX(TZX) - SBus - accelerated 24bit 3D card - max resolution ?(Leo)
* TCX - AFX - for Sparc 4 only - max. 1280x1024 @ 8bit
* TCX(S24) - AFX - for Sparc 5 only - max. 1152x900 @ 24bit
* Creator - SBus - max. 1280x1024 @ 24bit (FFB)
* Creator3D - SBus - max. 1920x1200 @ 24bit (FFB)
* ATI Mach64 - accelerated 8/24bit for Sparc64 PCI only
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