System hang when using SetMemoryAttributes

[Michael Zimmermann <sigmaepsilon92@gmail.com>]

Hi,

which side effects can SetMemoryAttributes have?
I have a device where setting the framebuffer(which is part of DRAM)
to EFI_MEMORY_UC makes UEFI hang later on(when already outside the lcd
driver).

If I do the same on a memory range allocated with AllocateAnyPages instead
of AllocateAddress UEFI boots just fine(but ofc, the screen doesn't work).

Unfortunately I don't have UART on that device but I'm sure there's no
assert because I configured DebugLib to reboot the device in that case -
which never happens, it's just stuck when the console drivers(TerminalDxe
etc) initialize later on.

Thanks
Michael