HackingVGAforFun
Aus LaborWiki
VGA
Video Graphics Adapter
pinouts
edid
EDID
I used EDID 1.3
Windows
- it accepts:
- standart timings
- established timings
- it looks like Windows XP doesn't like "prefered timings"
Linux
- The kernel module drm handels all the display stuff
- it accepts:
- established timings
- standart timings
- prefered timings
build a fake monitor
- Terminate the color lines with 75ohms
- Attach a 24C02 serial eeprom to the specified pins (24c04 - 24c16 is possible to )
flash a new edid
- Load the kernelmodule i2c-dev
- Get i2c-tools
- build the i2c-tools
- Become root: Sudo -s
- Add the tools folder to the PATH: PATH=$PATH:< ... >/i2c-tools/tools
- Run i2cdump to find the correct BUSID (device at 0x50 and 0x51)
- Flash new EDID with write-edid.sh
- Note the input file is plain/text with hexvalues, spaces and newlines only
create custom edid
- use Phoenix EDID Designer to create custom EDIDs
Note
- the tool outputs .dat-files, that need to be editet by hand, it contains invalid symbols
- you can use the export function to generate .raw files and use hexdump to convert them to plain/text hex
hack the kernel module drm
- install linux-source
- install linux-kernel-headers
- modify the Makefile
all: $(MAKE) -C $(KDIR) M=$(PWD) modules cp drm.ko /lib/modules/`uname -r`/kernel/drivers/gpu/drm cp drm_kms_helper.ko /lib/modules/`uname -r`/kernel/drivers/gpu/drm chmod 755 /lib/modules/`uname -r`/kernel/drivers/gpu/drm update-initramfs -u
- patch drm_edid.c , it doesn't accept vsync_width OR hsync_width to be 0
Results
Mesa 9.0
| Label | EDID Value | Description |
|---|---|---|
| AMD RV710 | Vsync = 0 | no graphics |
| AMD RV710 | Vsync = 1 | random graphics |
| AMD RV710 | Htotal = Hactive | no graphics |
| AMD RV710 | Hsync = 0 | normal graphics* |
| AMD RV710 | Vtotal = Vactive + 2 | random graphics |
- patched drm_edid.c