String Display during boot up

NTDEV
1

Hi all,

I know this has been discussed several times in the
list,
but Im still not able to get the hang of it.

Do ZwDisplayString/HalDisplayString work under W2K.

Or is there some other way to display the message on
the boot up screen and wait for some user input.

Inbv* functions??If yes then how do we use them?

regards
V.S.

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2

> Do ZwDisplayString/HalDisplayString work under W2K.

Yes, if you will call InbvEnableDisplayString(TRUE) first. The function
switches the boot GUI to a mode where ZwDisplayString works (like AUTOCHK).

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

3

Yup Max,
I did that.
But Im not seeing anything.
I used the code which was posted in the archives
sometime back.
The author said that they were written by you only.
I did just as is specified in these lines.:frowning:

Any suggestions where I could have gone wrong??

regards
V.S.

You need to get a pointer to the function required
to enable the display
string function (Max wrote these functions):

// Pointer to InbvEnableDisplayString function
typedef VOID (*INBV_ENABLE_DISPLAY_STRING)(BOOLEAN);

// Points to the real InbvEnableDisplayString
function for this OS
version
// NULL if no such function
static INBV_ENABLE_DISPLAY_STRING
InbvEnableDisplayStringProc;

DriverEntry(…)
{
…
RtlInitUnicodeString(&Str,
L"InbvEnableDisplayString");
InbvEnableDisplayStringProc =
MmGetSystemRoutineAddress(&Str);
…
}

// Acquires a boot-stage display for ZwDisplayString
VOID AcquireDisplay(VOID)
{
if( InbvEnableDisplayStringProc != NULL )
(InbvEnableDisplayStringProc)(TRUE);
// Do nothing
return;
}

// Release a boot-stage display for ZwDisplayString
VOID ReleaseDisplay(VOID)
{
if( InbvEnableDisplayStringProc != NULL )
(InbvEnableDisplayStringProc)(FALSE);
// Do nothing
return;
}

sample(PUNICODE_STRING MyString)
{
…
AcquireDisplay();
ZwDisplayString(MyString);
// Do as much display work as you like using
ZwDisplayString()
// and release the display when you are done.
ReleaseDisplay();
…
}

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