Yesterday I talked about the KMDF log. The KMDF log is a great
tool to debug why a DDI call has failed or diagnose the cause of
a bugcheck in your driver. You can customize different
attributes of the log so that you can better debug your driver.
The customizations available to you are:   • The length of the
log   • The format of the output   • Verbose output When a
customization requires you to add or modify a registry value,
the value will always be under
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\<your
driver>\Parameters\WDF. WHDC has a great KMDF tip which
describes all of these options as well.  Length of the log
Every KMDF driver has a log associated with it (you cannot turn
it off). The default size of the log is one page (as defined by
PAGE_SIZE; 4K on x86 and x64 systems, 8K on IA64). Since the log
is measured by the size of a memory page it is not possible to
say exactly how many entries fit in the log, but one page
usually holds around 100 entries. You can increase the size of
the log by