Unicode string functions IRQLs


on the latest WDK documentation for RtlPrefixUnicodeString, I read
that it must be called at PASSIVE_LEVEL. I need it on a minifilter
preoperation calllback, so possibly at APC_LEVEL. Of course I
understand it can’t be called at DISPATCH_LEVEL, because it uses
character tables from paged memory, but why not APC? Is it a
documentation flaw? In the lists archive I read that
RtlUpcaseUnicodeChar was wrongly declared needing PASSIVE_LEVEL in the
past DDK editions, so maybe the documentation has not been updated for

As far as I see, RtlPrefixUnicodeString [1] implementation on ReactOS
uses only RtlUpcaseUnicodeChar (IRQL <=APC_LEVEL) and “APC-safe” code.
Is there something different in Microsoft implementation?

Thank you,

… [1] http://www.reactos.biz/generated/doxygen/d3/df4/unicode_8c.html#a25