linux-kernel - [PATCH 2/3] x86: avoid efi_reserve_boot

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Date:	Mon, 11 Nov 2013 19:15:57 -0700
From:	Jerry Hoemann <jerry.hoemann@...com>
To:	rob@...dley.net, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, matt.fleming@...el.com,
	yinghai@...nel.org, penberg@...nel.org, akpm@...ux-foundation.org,
	linux-doc@...r.kernel.org, linux-efi@...r.kernel.org,
	vgoyal@...hat.com
Cc:	linux-kernel@...r.kernel.org, jerry.hoemann@...com
Subject: [PATCH 2/3] x86: avoid efi_reserve_boot_services

Some platform have firmware that violate UEFI spec and access boot service
code or data segments after the system has called Exit Boot Services.

The call to efi_reserve_boot_services is a work around to avoid using
boot service memory until after the kernel has done Set Virtual Map.

However, this reservation fragments memory which can cause
large allocations early in boot (e.g. crash kernel) to fail.

Avoid calling efi_reserve_boot_services if the memmap
is "correct."

Signed-off-by: Jerry Hoemann <jerry.hoemann@...com>
---
 arch/x86/kernel/setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f0de629..1186ff9 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1074,7 +1074,7 @@ void __init setup_arch(char **cmdline_p)
 	 * The EFI specification says that boot service code won't be called
 	 * after ExitBootServices(). This is, in fact, a lie.
 	 */
-	if (efi_enabled(EFI_MEMMAP))
+	if (efi_enabled(EFI_MEMMAP) && !efi_enabled(EFI_MEMMAP_CORRECT))
 		efi_reserve_boot_services();
 
 	/* preallocate 4k for mptable mpc */
-- 
1.7.11.3

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