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intel-ixp42x-welltech-epbx100 no longer boot due to 463dbba4d189 ("ARM: 9104/2: Fix Keystone 2 kernel mapping regression")

DISCUSSION Corentin Labbe 2 participants 3 messages Sep 28, 2021 Arm (32-bit)

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Corentin Labbe

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#0 lore raw

Hello

I am working on puting my ixp4xx board on kernelCI.
But it no longer boot since 4.14.
It only prints "Starting kernelUncompressing Linux... done, booting the kernel." then nothing.

I bisected the break to 463dbba4d189 ("ARM: 9104/2: Fix Keystone 2 kernel mapping regression")

With this patch reverted on top of 4.14, 5.15-rc3 and next-20210927, the board boot successfully.

Regards

#1 lore raw

Hello Corentin,

Quoted 5 lines · Corentin Labbe

I am working on puting my ixp4xx board on kernelCI.
But it no longer boot since 4.14.
It only prints "Starting kernelUncompressing Linux... done, booting the kernel." then nothing.

I bisected the break to 463dbba4d189 ("ARM: 9104/2: Fix Keystone 2 kernel mapping regression")

I guess you build your kernel as big-endian.

These parts seem suspicious to me:

- str r8, [r5] @ Save physical start of kernel
+#ifdef CONFIG_CPU_ENDIAN_BE8
+ str r8, [r5, #4] @ Save physical start of kernel (BE)
+#else
+ str r8, [r5] @ Save physical start of kernel (LE)
+#endif

and

- str r3, [r5] @ Save physical end of kernel
+#ifdef CONFIG_CPU_ENDIAN_BE8
+ str r3, [r5, #4] @ Save physical end of kernel (BE)
+#else
+ str r3, [r5] @ Save physical end of kernel (LE)
+#endif

IXP4xx, being ARMv5, uses CONFIG_CPU_ENDIAN_BE32 (when configured as BE), but it needs the ", #4" as well.

I'd test with: #if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32 --
Krzysztof "Chris" Hałasa

Sieć Badawcza Łukasiewicz
Przemysłowy Instytut Automatyki i Pomiarów PIAP
Al. Jerozolimskie 202, 02-486 Warszawa

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#2 lore raw
Quoted 11 lines · Krzysztof Hałasa

Hello Corentin,

Quoted 5 lines · Corentin Labbe

I am working on puting my ixp4xx board on kernelCI.
But it no longer boot since 4.14.
It only prints "Starting kernelUncompressing Linux... done, booting the kernel." then nothing.

I bisected the break to 463dbba4d189 ("ARM: 9104/2: Fix Keystone 2 kernel mapping regression")

I guess you build your kernel as big-endian.

Hello

Yes, IXP4XX is by default BE.

Quoted 19 lines

These parts seem suspicious to me:

(quoted diff) +5 -1
-    str r8, [r5]            @ Save physical start of kernel
+#ifdef CONFIG_CPU_ENDIAN_BE8
+    str r8, [r5, #4]            @ Save physical start of kernel (BE)
+#else
+    str r8, [r5]            @ Save physical start of kernel (LE)
+#endif

and

(quoted diff) +5 -1
-    str r3, [r5]            @ Save physical end of kernel
+#ifdef CONFIG_CPU_ENDIAN_BE8
+    str r3, [r5, #4]            @ Save physical end of kernel (BE)
+#else
+    str r3, [r5]            @ Save physical end of kernel (LE)
+#endif
Quoted 4 lines

IXP4xx, being ARMv5, uses CONFIG_CPU_ENDIAN_BE32 (when configured as BE), but it needs the ", #4" as well.

I'd test with: #if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32

Thanks, with the following patch, my boards boots

arch/arm/kernel/head.S +2 -2
index 29070eb8df7d..3fc7f9750ce4 100644
@@ -253,7 +253,7 @@ __create_page_tables:
        add     r0, r4, #KERNEL_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
        ldr     r6, =(_end - 1)
        adr_l   r5, kernel_sec_start            @ _pa(kernel_sec_start)
-#ifdef CONFIG_CPU_ENDIAN_BE8
+#if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32
        str     r8, [r5, #4]                    @ Save physical start of kernel (BE)
 #else
        str     r8, [r5]                        @ Save physical start of kernel (LE)

@@ -266,7 +266,7 @@ __create_page_tables:
        bls     1b
        eor     r3, r3, r7                      @ Remove the MMU flags
        adr_l   r5, kernel_sec_end              @ _pa(kernel_sec_end)
-#ifdef CONFIG_CPU_ENDIAN_BE8
+#if defined CONFIG_CPU_ENDIAN_BE8 || defined CONFIG_CPU_ENDIAN_BE32
        str     r3, [r5, #4]                    @ Save physical end of kernel (BE)
 #else
        str     r3, [r5]                        @ Save physical end of kernel (LE)

Regards