how does windows identify the display number for multiple display monitors?

[Sen_L_Intel]

Dear,

at present, I connected FOUR external display monitors, through DDIB, DDIC, DDID and DDIE port. however, through OS's display control panel, I found the display order is display 1(DDIB), 2(DDIE), 3(DDIC), 4(DDID), I assumed it was 1(DDIB), 2(DDIC), 3(DDID), 4(DDIE). so it's confused.

hence, might you please show me how the OS identify the number or order for multiple display monitors? for example, it used the information AUX channel, or something in BIOS, or it just sorted at random, or there is some algorithm in VBios or GOP to detect how many display monitors connected, and how to sort them?

thanks,

-Edward

[idata]

Hello Lin_Edward,

Thank you for joining the Graphics community.

This is a combination of your chipset configuration, BIOS, VBIOS and operating system; however, in this case the best answer should be provided by the operating system developer. Since your question seems to be related to the algorithms in the code of the operating system, their support should be able to provide an accurate answer how the operating system interacts with these elements.

Regards,

Amy.

[Sen_L_Intel]

Dear Amy,

got that, and I had been looking for this topic in MSDN, and did not find anything about the strategy to identify the number of multiple monitor. I used to think it was related to the detected order from bios, or some potential rules.

anyway, thanks for your kindly response.

[idata]

/thread/112235 Lin_Edward let me check if there is more information from our end regarding your question, maybe I can find something helpful.

Regards,

Amy.

[idata]

/thread/112235 Lin_Edward, thank you for your patience.

I would like to add something to input # 1; Intel® HD Graphics driver will also be part of that combination, it will instruct the operating system how to assign monitor numbers to each device, and even the Microsoft Basic driver does this.

Now in order to try to further assist you; can you provide more details on what you are trying to accomplish? Are you writing your own application?

One more thing I would like to comment is that to this date the latest Intel® HD Graphics controllers can handle up to 3 simultaneous displays, I wanted to mentioned this since you commented about 4 displays.

Regards,

Amy.

[Sen_L_Intel]

Dear Amy,

Yes, you're right, maybe it's the key point here. customer used DDIB, DDIC, DDID, DDIE to connect four monitors at the same time, and assume the display order is 1, 2, 3, 4, however, the order of the fact is 1, 3, 4, 2. since DDIE is a little special which support VGA, so I wonder which one decided the order, Intel's driver or windows (OS)?

I will attach some picture later.

thanks,

-Edward

[idata]

Thanks for the pictures.

Edward, please let me double check that.

Regards,

Amy.

[idata]

Edward, thank you for your patience.

I would like to gather more information regarding your configuration, so for debugging purposes provide the information requested below;

Intel® System Support Utility

Download Intel® System Support Utility, find it here; https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility https://downloadcenter.intel.com/download/25293/Intel-System-Support-Utility

Run the .exe and select "Scan"

Save and include as an attachment.

DxDiag Instructions:

Click on the "Start Menu" -> Type "DxDiag" -> Press "Enter" -> Wait for the DirectX Diagnostic Tool to finish loading.

In the DirectX Diagnostic Tool, click "Save All Information" -> Save the file DxDiag.txt.

Include DxDiag.txt as an attachment.

DispDiag Instructions:

Click on the "Start Menu" -> Type "cmd" -> Then a command shell window will open.

In the command shell, type "dispdiag -out %homepath%\Desktop\DispDiag-Intel-Issue.dat" -> The command shell will output something similar to "Dump File: C:\Users\[username]\DispDiag-# -# -# -# .dat".

Locate the .dat file on your desktop and include DispDiag-Intel-Issue.dat as an attachment.

To attach a file, you must click "Use Advanced Editor" in the top right corner of the response box, then the "attach" option will appear in the bottom right corner of the response box.

Regards,

Amy.

[Sen_L_Intel]

Dear Amy,

thanks a lot for your instructions, and I've tried it on my laptop. All are ok except the third one, I can get the file like DispDiag-Intel-Issue.dat, but I could not get the file "C:\Users\[username]\DispDiag-# -# -# -# .dat". are they the same one? if not, please show me how to generate the later. I've run the command "dispdiag -out %homepath%\Desktop\DispDiag-Intel-Issue.dat" under the administrator priority. there is no *.dat file generated in "C:\Users\[username]\" folder.

thanks a lot,

-Edward

[idata]

Once you copy and paste the command line on the cmd window it will display a "Dump file", copy that line and paste it on the Windows search bar

Then right click on that file and click on "Open location", there you will find the file.

Let me know if that helps.

Regards,

Amy.

[Sen_L_Intel]

Dear Amy,

thanks for your message, and I've got the DispDiag-Intel-Issue.dat data based-on your command. my question is I don't know how to get the "C:\Users\[username]\DispDiag-# -# -# -# .dat" file. I assume they are the same file, am I right?

thanks,

-Edward

[idata]

Edward, yes that is correct, is the same file. Sorry, I misinterpreted your question.

Regards,

Amy.

[idata]

Edward, once you have those files please attach them.

To attach a file, you must click "Use Advanced Editor" in the top right corner of the response box, then the "attach" option will appear in the bottom right corner of the response box.

Regards,

Amy.

[Sen_L_Intel]

Amy,

thanks for your kindly reminding, please check the attachment for the information of the customers' system.

[idata]

Thank you for the files.

I will continue reviewing this matter, and update the thread as soon as possible.

Regards,

Amy.

[idata]

Edward, thank you for your patience.

In this case, the driver assigns the ID number to each display upon detection, detection is handled with a function from the operating system.

Regards,

Amy.

[Sen_L_Intel]

Amy,

thanks a lot, and so you mean, Driver only assign ID number based-on the detection, and the detection is doing by operating system. I assume the detection should be done during POS stage, (before entering into OS), so that I can see the monitors information through BIOS. when booting up, the system would do self-detection, so it should be done by BIOS, right?

BTW: might I please know which message let you see the consequence?

thanks,

-Edward

[idata]

Please, let me double check that.

Regards,

Amy.

[idata]

Well it is not BIOS since drivers do not work there, but in the operating system. The system recognizes all hardware during POST, but the detection is when the operating system starts to load.

Regards,

Amy.

[idata]

Hope you were able to see my last input.

If you need further assistance let us know.

Regards,

Amy.