Windows Boot Manager - how to force the BIOS calls for display ?

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

I would like to ask if anyone does have any idea if the windows boot manager
is using BIOS calls to display the boot menu options. It is important for me
because if it is not like that, I will never see the boot menu with the SOL
capability of Intel vPro.

According to my experience it looks like the windows boot manager is using
the BIOS calls if it is booted from CD/DVD (like Windows Vista DVD or WinPE
build with Windows AIK), but it is not using these calls if it is booted from
HDD. Sounds weird ? Yes, but it is just like that !

Does anyone know a way how to switch the Windows Boot Manager to use the
BIOS calls for displaying text based output if it is booted from HDD ?

thanks
 
Not certain if I understand correctly. Is it that you want to see the
startup text screen during boot rather that the manufacturers screen? If so,
the manufacturers screen can usually be deactivated in the bios.

--


Regards,

Richard Urban MVP
Microsoft Windows Shell/User
 
No.

To be more specific:

Some BIOSes can send to the COM port all the text that is printed on the
screen through BIOS calls. So you can attach some kind of terminal to the COM
port (like connect another PC with serial cable like in the old times and run
the terminal application on the receiving COM port on it) and read all the
BIOS messages and also send commands to the "remote" BIOS. Basically you have
a remote terminal with keyboard and display connected over serial cable so
you have something which is called "headless system" - no keyboard or display
is actually attached to the managed PC.

Then there is this Intel vPro platform which has a nice part called Intel
AMT. This AMT can do one really amazing thing called Serial-over-LAN (SOL)
that can encapsulate the traffic going to the COM port into TCP/IP packets
and send it over LAN.

So if you combine the two things above, you can have all the serial port
trafic generated by BIOS nicely piped over LAN (and of course even Internet)
in the TCP/IP packets. Therefore you do not need to connect the serial cable
to the headless system, but instead you connect just the ethernet cable.

This works nice if you want to browse the machine BIOS settings or if you
want to do the one time boot device selection or ask for the PXE boot by
pressing F12.

The problem now is:
why the Windows Vista Boot Manager can not be viewed through SOL ? is it
because it is not using the BIOS calls to write the text to the screen ? How
to force it to use the BIOS calls ?
 
On Wed, 21 Mar 2007 02:07:11 -0700, Zdenek Hrib <Zdenek
I would like to ask if anyone does have any idea if the windows boot manager
is using BIOS calls to display the boot menu options. It is important for me
because if it is not like that, I will never see the boot menu with the SOL
capability of Intel vPro.

According to my experience it looks like the windows boot manager is using
the BIOS calls if it is booted from CD/DVD (like Windows Vista DVD or WinPE
build with Windows AIK), but it is not using these calls if it is booted from
HDD. Sounds weird ? Yes, but it is just like that !
Click to expand...

What makes you say this? If you're referring to the Vista boot manager
that allows you to fall back to the XP boot.ini menu, then it's
running using the BIOS.
If you give the computer the three finger salute, and it reboots, then
the BIOS is still being used for I/O.
 
Well I am pretty sure I can not fall back to boot.ini, if we are talking just
about Windows Vista and not about XP (at all).

Maybe the XP boot manager is using BIOS calls, but that will not help me.

It looks like that after reboot the BIOS display calls is used only during
the POST (well, some parts of the POST) and then everyone is trying to bypass
it, because it is slow. Of course if you boot to DOS you can be probably sure
that the BIOS calls will be used, but that won't help me either.
 
Hello,
Try looking at this option:
Open an elevated cmd prompt.
Run bcdedit /ems /? and bcdedit /emssettings /?
This may be want you are asking for.
This allows you to redirect the screen outboot via a port to terminal.
Thanks,
Darrell Gorter[MSFT]

This posting is provided "AS IS" with no warranties, and confers no rights
--------------------
|>Thread-Topic: Windows Boot Manager - how to force the BIOS calls for
display
|>thread-index: Acdrz1/OLjscJXqqRIiMvk1iIVR+fw==
|>X-WBNR-Posting-Host: 193.179.209.52
|>From: =?Utf-8?B?WmRlbmVrIEhyaWI=?= <[email protected]>
|>References: <[email protected]>
<[email protected]>
|>Subject: Re: Windows Boot Manager - how to force the BIOS calls for
display
|>Date: Wed, 21 Mar 2007 08:41:21 -0700
|>Lines: 31
|>Message-ID: <[email protected]>
|>MIME-Version: 1.0
|>Content-Type: text/plain;
|> charset="Utf-8"
|>Content-Transfer-Encoding: 7bit
|>X-Newsreader: Microsoft CDO for Windows 2000
|>Content-Class: urn:content-classes:message
|>Importance: normal
|>Priority: normal
|>X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.2757
|>Newsgroups: microsoft.public.windows.vista.installation_setup
|>Path: TK2MSFTNGHUB02.phx.gbl
|>Xref: TK2MSFTNGHUB02.phx.gbl
microsoft.public.windows.vista.installation_setup:13185
|>NNTP-Posting-Host: tk2msftsbfm01.phx.gbl 10.40.244.148
|>X-Tomcat-NG: microsoft.public.windows.vista.installation_setup
|>
|>No.
|>
|>To be more specific:
|>
|>Some BIOSes can send to the COM port all the text that is printed on the
|>screen through BIOS calls. So you can attach some kind of terminal to the
COM
|>port (like connect another PC with serial cable like in the old times and
run
|>the terminal application on the receiving COM port on it) and read all
the
|>BIOS messages and also send commands to the "remote" BIOS. Basically you
have
|>a remote terminal with keyboard and display connected over serial cable
so
|>you have something which is called "headless system" - no keyboard or
display
|>is actually attached to the managed PC.
|>
|>Then there is this Intel vPro platform which has a nice part called Intel
|>AMT. This AMT can do one really amazing thing called Serial-over-LAN
(SOL)
|>that can encapsulate the traffic going to the COM port into TCP/IP
packets
|>and send it over LAN.
|>
|>So if you combine the two things above, you can have all the serial port
|>trafic generated by BIOS nicely piped over LAN (and of course even
Internet)
|>in the TCP/IP packets. Therefore you do not need to connect the serial
cable
|>to the headless system, but instead you connect just the ethernet cable.
|>
|>This works nice if you want to browse the machine BIOS settings or if you
|>want to do the one time boot device selection or ask for the PXE boot by
|>pressing F12.
|>
|>The problem now is:
|>why the Windows Vista Boot Manager can not be viewed through SOL ? is it
|>because it is not using the BIOS calls to write the text to the screen ?
How
|>to force it to use the BIOS calls ?
|>
 
BIOS "calls" are software interrupts (versus hardware) and, to best of my
knowledge, are assembly language "runs". Quoted from your post:

"...can do one really amazing thing called Serial-over-LAN (SOL)
that can encapsulate the traffic going to the COM port into TCP/IP packets
and send it over LAN.
So if you combine the two things above, you can have all the serial port
trafic generated by BIOS nicely piped over LAN (and of course even Internet)
....."

Sorry but, at least it seems to me, the statements appear contradictory - I
believe there are about 40 - 50 BIOS calls and none that I know of that
"generate" traffic (not same as "output" or function of the call).
 
Well the point is that after the program writes a message to the screen and
uses BIOS calls for this "message display" the BIOS internaly directs this
output not only to the screen but also to the serial port. So you really do
not write to the COM port - you write to the the screen as always and serial
port matters are done behind the scenes.
 
Thank you for your answer.

Actually I am using the bcdedit, and the parameter which allows to display
the windows boot menu by SOL is called "bootems"and must be set to "yes" on
the Windows Boot Manager Object. But anyway I would like to ask if anyone
knows how this works internally. It looks like this "bootems" does not force
the Windows Boot Manager to use the BIOS calls, but it just forces the
Windows Boot Manager to write to the serial port too (on his own - bypassing
the BIOS call fro writing to the screen).
 
Hello,
Try technet:
http://technet2.microsoft.com/WindowsServer/en/library/ff4bc645-cb49-4959-88
9a-9f92d04b0dda1033.mspx?mfr=true
If you are using boot manager settings you are directing the OS to report
over the port.
http://technet2.microsoft.com/WindowsServer/en/library/ff4bc645-cb49-4959-88
9a-9f92d04b0dda1033.mspx?mfr=true

These explain how it works but yes those settings redirect Windows output
and control through the port.

Thanks,
Darrell Gorter[MSFT]

This posting is provided "AS IS" with no warranties, and confers no rights
--------------------
|>Thread-Topic: Windows Boot Manager - how to force the BIOS calls for
display
|>thread-index: AcdsUoOY84MR6hJpRhKmunR88W1ziA==
|>X-WBNR-Posting-Host: 193.179.209.52
|>From: =?Utf-8?B?WmRlbmVrIEhyaWI=?= <[email protected]>
|>References: <[email protected]>
<[email protected]>
<[email protected]>
<[email protected]>
|>Subject: Re: Windows Boot Manager - how to force the BIOS calls for
display
|>Date: Thu, 22 Mar 2007 00:20:05 -0700
|>Lines: 23
|>Message-ID: <[email protected]>
|>MIME-Version: 1.0
|>Content-Type: text/plain;
|> charset="Utf-8"
|>Content-Transfer-Encoding: 7bit
|>X-Newsreader: Microsoft CDO for Windows 2000
|>Content-Class: urn:content-classes:message
|>Importance: normal
|>Priority: normal
|>X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.2757
|>Newsgroups: microsoft.public.windows.vista.installation_setup
|>Path: TK2MSFTNGHUB02.phx.gbl
|>Xref: TK2MSFTNGHUB02.phx.gbl
microsoft.public.windows.vista.installation_setup:13278
|>NNTP-Posting-Host: tk2msftsbfm01.phx.gbl 10.40.244.148
|>X-Tomcat-NG: microsoft.public.windows.vista.installation_setup
|>
|>Thank you for your answer.
|>
|>Actually I am using the bcdedit, and the parameter which allows to
display
|>the windows boot menu by SOL is called "bootems"and must be set to "yes"
on
|>the Windows Boot Manager Object. But anyway I would like to ask if anyone
|>knows how this works internally. It looks like this "bootems" does not
force
|>the Windows Boot Manager to use the BIOS calls, but it just forces the
|>Windows Boot Manager to write to the serial port too (on his own -
bypassing
|>the BIOS call fro writing to the screen).
|>
|>
|>
|>""Darrell Gorter[MSFT]"" wrote:
|>
|>> Hello,
|>> Try looking at this option:
|>> Open an elevated cmd prompt.
|>> Run bcdedit /ems /? and bcdedit /emssettings /?
|>> This may be want you are asking for.
|>> This allows you to redirect the screen outboot via a port to terminal.
|>> Thanks,
|>> Darrell Gorter[MSFT]
|>
|>
 
Back
Top