On Thu, 2013-09-12 at 20:25 +0200, Christophe Leroy wrote:Most probably. It is step 2 of the process defined in MPC866 and MPC885 Reference Manuals:This is a reorganisation of the setup of the TLB at kernel startup, in orderIs this change to make sure we invalidate everything even if the
to handle the CONFIG_PIN_TLB case in accordance with chapter 8.10.3 of MPC866
and MPC885 reference manuals.
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
diff -ur linux-3.11.org/arch/powerpc/kernel/head_8xx.S linux-3.11/arch/powerpc/kernel/head_8xx.S
--- linux-3.11.org/arch/powerpc/kernel/head_8xx.S 2013-09-02 22:46:10.000000000 +0200
+++ linux-3.11/arch/powerpc/kernel/head_8xx.S 2013-09-09 11:28:54.000000000 +0200
@@ -785,27 +785,24 @@
* these mappings is mapped by page tables.
*/
initial_mmu:
- tlbia /* Invalidate all TLB entries */
-/* Always pin the first 8 MB ITLB to prevent ITLB
- misses while mucking around with SRR0/SRR1 in asm
-*/
- lis r8, MI_RSV4I@h
- ori r8, r8, 0x1c00
-
+ lis r8, MI_RESETVAL@h
mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
-#ifdef CONFIG_PIN_TLB
- lis r10, (MD_RSV4I | MD_RESETVAL)@h
- ori r10, r10, 0x1c00
- mr r8, r10
-#else
lis r10, MD_RESETVAL@h
-#endif
#ifndef CONFIG_8xx_COPYBACK
oris r10, r10, MD_WTDEF@h
#endif
mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
+ tlbia /* Invalidate all TLB entries */
bootloader set RSV4I?
Yes, I kept the same entries in order to limit modifications:
+ ori r8, r8, 0x1c00Still 0x1c00?
+ mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
+#ifdef CONFIG_PIN_TLB
+ ori r10, r10, 0x1c00
+ mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
+#endif
Here we are not trying to pin entry 0. We are at step 8, we are setting MI_RSV4I. At the same time, we set MD_CTR to 0 which is off the pinned range, to be sure that we won't overwrite one of the pinned entries.
/* Now map the lower 8 Meg into the TLBs. For this quick hack,Entry 0 is not pinnable.
* we can load the instruction and data TLB registers with the
* same values.
@@ -825,6 +822,12 @@
mtspr SPRN_MI_AP, r8
mtspr SPRN_MD_AP, r8
+ /* Always pin the first 8 MB ITLB to prevent ITLB
+ * misses while mucking around with SRR0/SRR1 in asm
+ */
+ lis r8, (MI_RSV4I | MI_RESETVAL)@h
+ mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */