Impact: cleanup

We are in setup stage so we use GLOBAL
instead of ENTRY and do not increase code
size.
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Jeremy Fitzhardinge wrote:
>
> Maybe it really does require the far jump immediately after setting PE
> in cr0...
>
> Hm, I don't remember this paragraph being in vol 3a, section 8.9.1
> before.  Is it a recent addition?
>
>    Random failures can occur if other instructions exist between steps
>    3 and 4 above.  Failures will be readily seen in some situations,
>    such as when instructions that reference memory are inserted between
>    steps 3 and 4 while in system management mode.
>

I don't remember that, either.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Remove old comments that include the old arch/i386 directory.
Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

To set CR0.PE, use the X86_CR0_PE macro defined in
<asm/processor-flags.h> instead of hardcoding it as a constant (1).
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Intel VT doesn't like to engage when the protected-mode state isn't
fully initialized.  Make life easier for it by initializing LDTR (to
null) and TR (to a dummy hunk of low memory which will never actually
be touched.)
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Make the transition to protected mode more paranoid by having
back-to-back near jump (to synchronize the 386/486 prefetch queue) and
far jump (to set up the code segment.)

While we're at it, zero as many registers as practical (for future
expandability of the 32-bit entry interface) and enter 32-bit mode
with a valid stack.  Note that the 32-bit code cannot rely on this
stack, or we'll break all other existing users of the 32-bit
entrypoint, but it may make debugging hacks easier to write.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

In accordance with the newly formalized 32-bit boot protocol, set
%ebx == %ebp == %edi == 0 in order to support future extensions to the
protocol.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

The 386 and 486 needs a jump immediately after setting %cr0 in order
to serialize the pipeline.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This is the code which actually does the switch to protected mode,
including all preparation.  It is also responsible for invoking the
boot loader hooks, if present.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>