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From: Alexey Kardashevskiy <>
Cc: Alexey Kardashevskiy <>
Subject: [RFC PATCH kernel] powerpc: Fix early setup to make early_ioremap work
Date: Thu, 20 May 2021 13:29:19 +1000	[thread overview]
Message-ID: <> (raw)

The immediate problem is that after
0bd3f9e953bd ("powerpc/legacy_serial: Use early_ioremap()")
the kernel silently reboots. The reason is that early_ioremap() returns
broken addresses as it uses slot_virt[] array which initialized with
KERN_IO_END- FIXADDR_SIZ + FIXADDR_SIZE == __kernel_io_end which is 0
when early_ioremap_setup() is called. __kernel_io_end is initialized
little bit later in early_init_mmu().

This fixes the initialization by swapping early_ioremap_setup and

This also fixes IOREMAP_END to use FIXADDR_SIZE defined just next to it,
seems to make sense, unless there is some weird logic with redefining
FIXADDR_SIZE as the compiling goes.

Signed-off-by: Alexey Kardashevskiy <>
 arch/powerpc/include/asm/book3s/64/pgtable.h | 2 +-
 arch/powerpc/kernel/setup_64.c               | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index a666d561b44d..54a06129794b 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -325,8 +325,8 @@ extern unsigned long pci_io_base;
 #define IOREMAP_START	(ioremap_bot)
 #define FIXADDR_SIZE	SZ_32M
 /* Advertise special mapping type for AGP */
 #define HAVE_PAGE_AGP
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index b779d25761cf..ce09fe5debf4 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -369,11 +369,12 @@ void __init early_setup(unsigned long dt_ptr)
-	early_ioremap_setup();
 	/* Initialize the hash table or TLB handling */
+	early_ioremap_setup();
 	 * After firmware and early platform setup code has set things up,
 	 * we note the SPR values for configurable control/performance

             reply	other threads:[~2021-05-20  3:29 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20  3:29 Alexey Kardashevskiy [this message]
2021-05-20  3:33 ` [RFC PATCH kernel] powerpc: Fix early setup to make early_ioremap work Alexey Kardashevskiy
2021-05-20  5:38   ` Christophe Leroy
2021-05-20  5:46 ` Christophe Leroy
2021-05-20  5:52   ` Alexey Kardashevskiy
2021-05-20  6:03     ` Christophe Leroy
2021-05-21 12:44 ` Michael Ellerman

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