On 11/05/2015 17:36, Laszlo Ersek wrote: > It's not about feature detection -- the question (from > <553f4d23.3060...@redhat.com>) is whether I should set APMC_EN myself > *every time* before writing to APM_CNT, in the > EFI_SMM_CONTROL2_PROTOCOL.Trigger() method. That protocol is provided by > a runtime DXE driver and would be exercised by eg. the non-privileged > half of the runtime variable service driver.
Oh sorry, I couldn't find that message ID. > It's no problem to set it, I have the code ready, I was just wondering > if I should keep that hunk. (In fact it might not even matter: if the OS > interferes and clears APMC_EN before the non-privileged half mentioned > above manages to raise the SMI, then the call / transition to SMM will > simply not happen, which is bad for the OS, and probably irrelevant for > the firmware (... the security thereof).) The OS can also race against you and clear APMC_EN, so it's even unnecessary to reset it. Paolo
