On 02/01/13 19:28, David Hubbard wrote:
Andrew, Ron, what's your take on http://mjg59.dreamwidth.org/20916.html ?
Specifically: "This is part of Windows 8's fast boot support - the keyboard may not be initialised until after the OS has started."
OK, the feature is deferred initialisation of USB devices until they are actually needed. Windows 8 is making use of this but it is introduced as part of the UEFI spec 2.3.1c. This is optional to implement it or not, OEM gets to decide. This is in the UEFI spec and can be used by other OSes than Windows eg Grub could use it to speed up loading of Linux.
- User is thus *forced* to use Win8's "hold down shift and restart"
feature -- adding another barrier before a user can boot her own OS.
I think the biggest problem here is that the entire BIOS is made inaccessible, and only if Windows gives permission can you change that.
Well yes and no. 1) PS/2 keyboards are not affected, they are still initialised and available as normal. Many laptop keyboards are implemented as PS/2 devices. 2) There are a number of ways that you can get USB enumerated and keyboards initialised. a) If HDD is not primary boot target b) If primary boot target fails c) If bootloader invokes EFI_SIMPLE_TEXT_INPUT_EX_PROTOCOL. ReadKeyStrokeEx()
So yes, on a motherboard that implements it, with no PS/2 keyboard, with the HDD as primary boot target and with Win8 installed then you may have to use the Win8 menu to restart into the UEFI settings screens. And yes this can be a small barrier to booting using an alternative method for any reason, not just installing an alternative OS. But quite frankly I have seen some bizarre setup screens on legacy BIOS that made choosing to boot from a USB device an exercise in frustration. So this extra step in the road to booting an alternate OS is not that big a deal. It can at least be documented and is not a hard thing to do at all. Even without this there are some machines that boot so fast it is not easy to press the key to get to the setup screens at the right time, this may actually give a more reliable way to get to the setup screens on those machines.
Regards, David
BTW 1) when you use BIOS above, you actually mean Setup. Setup is an application launched by the BIOS to view or change system settings. The BIOS is not accessible nor inaccessible, it is running as soon as the CPU begins to execute code and will complete its tasks as normal according to those system settings. BTW 2) its UEFI firmware, not BIOS. Just as coreboot is not BIOS.
Best wishes, Andrew