Commit 216705d2 authored Jul 02, 2008 by Hugh Dickins Committed by Ingo Molnar Jul 03, 2008

x86: fix Intel Mac booting with EFI



Fedora reports that mem_init()'s zap_low_mappings(), extended to SMP in
61165d7a x86: fix app crashes after SMP
resume causes 32-bit Intel Mac machines to reboot very early when
booting with EFI.

The EFI code appears to manage low mappings for itself when needed; but
like many before it, confuses PSE with PAE.  So it has only been mapping
half the space it needed when PSE but not PAE.  This remained unnoticed
until we moved the SMP zap_low_mappings() before
efi_enter_virtual_mode().  Presumably could have been noticed years ago
if anyone ran a UP kernel on such machines?

Reported-by: Peter Jones <pjones@redhat.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Glauber Costa <gcosta@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Peter Jones <pjones@redhat.com>

parent efac4189

arch/x86/kernel/efi_32.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -49,13 +49,13 @@ void efi_call_phys_prelog(void)
		local_irq_save(efi_rt_eflags);

		/*
		* If I don't have PSE, I should just duplicate two entries in page
		* directory. If I have PSE, I just need to duplicate one entry in
		* If I don't have PAE, I should just duplicate two entries in page
		* directory. If I have PAE, I just need to duplicate one entry in
		* page directory.
		*/
		cr4 = read_cr4();

		if (cr4 & X86_CR4_PSE) {
		if (cr4 & X86_CR4_PAE) {
		efi_bak_pg_dir_pointer[0].pgd =
		swapper_pg_dir[pgd_index(0)].pgd;
		swapper_pg_dir[0].pgd =
		@@ -93,7 +93,7 @@ void efi_call_phys_epilog(void)

		cr4 = read_cr4();

		if (cr4 & X86_CR4_PSE) {
		if (cr4 & X86_CR4_PAE) {
		swapper_pg_dir[pgd_index(0)].pgd =
		efi_bak_pg_dir_pointer[0].pgd;
		} else {