Acer Aspire 5740G BIOS hacking (Switchable Graphics - not yet)

[zfeet]

I have already mentioned it few times, but in this stage it will be very helpful to have schematics of the laptop's motherboard, so we can finally puzzle out what is that mysterious GPIO 37 input pin. There are few sites which sell laptop schematics, but I haven't found any that provides schematics for this laptop, yet.

Hello and thanks for your work so far! I've contacted some people who might get the schematics and I'll let you know if I get them as well.

[sustmi]

What happens if you??

1. enable the IGP using DIY ViDock Setup 1.x, do a PCI compaction on it
2. chainload to Win7, load the driver for the IGP ensuring it's enabled with no error 12.
3. try disabling/enabling the IGP and the primary video card.

Does the LCD flash during (3). If so, then that would indicate there is a MUX present and indeed bios hacking to enable the IGP and make it the primary bootup card is worth pursuing.

I tried to play with DIY ViDock, but everytime I enable IGD and try to boot W7,
I get BSOD with STOP 0x000000A5 and immediate reboot.
Linux boots, but IGD doesn't work.
The problem is in configuration of GGC - Processor Graphics Control Register of PCI device 00:00.0 (see documentation p. 57).

My configuration is:
IGD VGA Disable (IVD) = 1h

1 = Disable. Device 2 (IGD) does not claim VGA cycles (Mem and IO), and the Sub- Class Code field within Device 2 function 0 Class Code register is 80.

Graphics Mode Select (GMS) = 0h

0h: No memory pre-allocated. Device 2 (IGD) does not claim VGA cycles (Mem and IO), and the Sub-Class Code field within Device 2 Function 0 Class Code register is 80.

GTT Graphics Memory Size (GGMS) = 0h

0h: No memory pre-allocated. GTT cycles (Mem and IO) are not claimed.

These settings fundamentally means, that IGD is disabled. Yes, it's powered-on by DEVEN PCI register of 00:00.0, bit 3 = 1.
But the IGD device (00:02.0) doesn't play like VGA adapter.
Unfortunately this configuration can be set only in BIOS boot stage (in DIY ViDock it's already locked).

Note: This register is locked and becomes Read Only when the D_LCK bit in the SMRAM register is set.

I found PCI dump from HP G62 140 which should have IGD working.
This is the configuration:
IGD VGA Disable (IVD) = 0h

0 = Enable. Device 2 (IGD) claims VGA memory and IO cycles, the Sub-Class Code within Device 2 Class Code register is 00.

Graphics Mode Select (GMS) = 5h (32MB)

5h-Dh: DVMT (UMA) mode, memory pre-allocated for frame buffer, in quantities as shown in the Encoding table.

GTT Graphics Memory Size (GGMS) = 3h

3h: No Intel VT-d mode, 2 MB of memory pre-allocated for GTT.

[sustmi]

Actually I found the part of code in one of the BIOS modules which configures this register (GGC).
It's PlatformStage2 (file 30303030-3030-3732-0000-000000000000.PEI).
The configuration is done when the Primary Display option (in BIOS Setup) is set to SG.
I'm not an expert, but I think that BIOS configures the register properly (according to DVMT Preallocated option).
However, when [I]Primary Display[/I is set to SG, laptop doesn't boot (hangs probably somewhere in early BIOS stages).

Currently, I see the only way how to find out the cause of hang in hacking the PlatformStage2 module.
I mean trying to bypass individual parts of code until the cause is identified.
Unluckily this is not an easy task, because you can't just use printf, to print out checkpoints where the code get yet.

If anybody knows a way how to "output" in BIOS stage, I'm listening.
I've been thinking about something like blinking the num-lock LED or beeping with the speaker, but I'm not sure if this is possible in the early boot stages.

[sustmi]

Maybe some BIOS POST code reading debug board could help.
I must look for a board which can be used with my laptop.
I remember I saw POST displays for USB port, but I wonder if they can catch POST codes in early stages...

EDIT: Nope, there probably aren't any boards for USB (USB is used only for power supply).
So, only Mini PCI-E comes into the account. (I suppose 5740G does have one.)
Something like this: http://www.dealextreme.com/photogallery.dx/sku.37916

[ouzo]

5740g has 2 pcie slots, one is used for wireless and an other it's free

[racingpht]

Hi Sustmi, sorry for a bit out of topic but very related to your research,

I bought 5740dg and managed to install 1 HDD caddy into the DVD slot. But this caddy only works for bios v1.16 and suffered from some random screen artifacts. As long as I know 1.22 has changed its VGA bios to fix some powerplay stuff, but it also removed the support of the 2nd ATAPI device. Do you think it's possible to replace the VGA part of 1.16 with the 1.22 one? Thanks in advance,

[AlexFLCL]

I broke my bios trying to flash it with the 1.10 version. Now when I switch it on it turns the screen in black and makes nothing!.

Do you think I can repair the laptop with that crisis disk?

Thank you guys =).

[downloads]

@AlexFLCL That's what the crisis disk is for- go ahead.

[sustmi]

Hi Sustmi, sorry for a bit out of topic but very related to your research,

I bought 5740dg and managed to install 1 HDD caddy into the DVD slot. But this caddy only works for bios v1.16 and suffered from some random screen artifacts. As long as I know 1.22 has changed its VGA bios to fix some powerplay stuff, but it also removed the support of the 2nd ATAPI device. Do you think it's possible to replace the VGA part of 1.16 with the 1.22 one? Thanks in advance,

Hi. Yes, it could be possible.
VGA BIOS is just one of the files you get when you extract BIN/WPH image using Phoenix SLIC mod tool.
I'll try to build it for you soon. But be aware that it is possible that BIOS will not boot.
Better prepare the Crisis Disk.

[AlexFLCL]

@AlexFLCL That's what the crisis disk is for- go ahead.

Ok, Then I will ask for my laptop.