[PATCH] powerpc/40x: Map 32Mbytes of memory at startup

From: Christophe Leroy
Date: Mon Sep 27 2021 - 06:35:32 EST


As reported by Carlo, 16Mbytes is not enough with modern kernels
that tend to be a bit big, so map another 16M page at boot.

Cc: cp <carlojpisani@xxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/kernel/head_40x.S | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 7d72ee5ab387..5fce4680d2d3 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -650,7 +650,7 @@ start_here:
b . /* prevent prefetch past rfi */

/* Set up the initial MMU state so we can do the first level of
- * kernel initialization. This maps the first 16 MBytes of memory 1:1
+ * kernel initialization. This maps the first 32 MBytes of memory 1:1
* virtual to physical and more importantly sets the cache mode.
*/
initial_mmu:
@@ -687,6 +687,12 @@ initial_mmu:
tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */
tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */

+ li r0,62 /* TLB slot 62 */
+ addis r4,r4,SZ_16M
+ addis r3,r3,SZ_16M
+ tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */
+ tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */
+
isync

/* Establish the exception vector base
--
2.31.1