What happens if we set MDL_MAPPING_CAN_FAIL bit in the IRP receiv ed ?

NTDEV
1

Hi all

I have a question regarding MDL_MAPPING_CAN_FAIL bit setting in
IrpMdl->Flags . Walter Oney book clearly says we should not set the above
bit since MDL is supposed to be an Opaque structure . Because I have to
implement the driver to work in 98 and 2K environments. Can anybody explain
what exactly will happen if we set ourselves this bit ?

And I could not find any information regarding MmMapLockedPagesSpecifyCache
function support in Windows 98 . Where as other functions that are not
supported in Win98 clearly says that they could not supported in Windows 98.
Is this a Document bug ?

Thanks in advance
srinivasa