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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>, scottwood@freescale.com
Subject: [PATCH] powerpc 8xx: Loading kernels over 8Mbytes without
 CONFIG_PIN_TLB
Message-Id: <20131127110406.6DC8E1A504F@localhost.localdomain>
Date: Wed, 27 Nov 2013 12:04:06 +0100 (CET)
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
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Today, the only way to load kernels whose size is greater than 8Mbytes is to
activate CONFIG_PIN_TLB. Otherwise, the physical memory initially mapped is
limited to 8Mbytes. This patch sets up 24 Mbytes of initial memory regardless
of whether CONFIG_PIN_TLB is active or not. It allows to load "big" kernels
(for instance when activating CONFIG_LOCKDEP_SUPPORT) without having
to activate CONFIG_PIN_TLB.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

diff -ur a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -841,11 +841,12 @@
 	ori	r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
 	mtspr	SPRN_MD_RPN, r8
 
-#ifdef CONFIG_PIN_TLB
 	/* Map two more 8M kernel data pages.
 	*/
+#ifdef CONFIG_PIN_TLB
 	addi	r10, r10, 0x0100
 	mtspr	SPRN_MD_CTR, r10
+#endif
 
 	lis	r8, KERNELBASE@h	/* Create vaddr for TLB */
 	addis	r8, r8, 0x0080		/* Add 8M */
@@ -858,15 +859,16 @@
 	addis	r11, r11, 0x0080	/* Add 8M */
 	mtspr	SPRN_MD_RPN, r11
 
+#ifdef CONFIG_PIN_TLB
 	addi	r10, r10, 0x0100
 	mtspr	SPRN_MD_CTR, r10
+#endif
 
 	addis	r8, r8, 0x0080		/* Add 8M */
 	mtspr	SPRN_MD_EPN, r8
 	mtspr	SPRN_MD_TWC, r9
 	addis	r11, r11, 0x0080	/* Add 8M */
 	mtspr	SPRN_MD_RPN, r11
-#endif
 
 	/* Since the cache is enabled according to the information we
 	 * just loaded into the TLB, invalidate and enable the caches here.
diff -ur a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -213,12 +213,7 @@
 	 */
 	BUG_ON(first_memblock_base != 0);
 
-#ifdef CONFIG_PIN_TLB
 	/* 8xx can only access 24MB at the moment */
 	memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01800000));
-#else
-	/* 8xx can only access 8MB at the moment */
-	memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
-#endif
 }
 #endif /* CONFIG_8xx */