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Subject[tip:x86/microcode] x86/microcode: Disable builtin microcode loading on 32-bit for now
Commit-ID:  ee38a90709084b1c91279cde8f783e90f85285a1
Author: Borislav Petkov <>
AuthorDate: Thu, 4 Jun 2015 18:55:27 +0200
Committer: Ingo Molnar <>
CommitDate: Sun, 7 Jun 2015 15:38:14 +0200

x86/microcode: Disable builtin microcode loading on 32-bit for now

Andy Shevchenko reported machine freezes when booting latest tip
on 32-bit setups. Problem is, the builtin microcode handling cannot
really work that early, when we haven't even enabled paging.

A proper fix would involve handling that case specially as every
other early 32-bit boot case in the microcode loader and would
require much more involved changes for which it is too late now,
more than a week before the upcoming merge window.

So, disable the builtin microcode loading on 32-bit for now.

Reported-and-tested-by: Andy Shevchenko <>
Signed-off-by: Borislav Petkov <>
Cc: Andrew Morton <>
Cc: H. Peter Anvin <>
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Thomas Gleixner <>
Signed-off-by: Ingo Molnar <>
arch/x86/kernel/cpu/microcode/amd_early.c | 4 ++++
arch/x86/kernel/cpu/microcode/intel_early.c | 4 ++++
2 files changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/amd_early.c b/arch/x86/kernel/cpu/microcode/amd_early.c
index 9208a36..9243cd8 100644
--- a/arch/x86/kernel/cpu/microcode/amd_early.c
+++ b/arch/x86/kernel/cpu/microcode/amd_early.c
@@ -230,6 +230,7 @@ static void apply_ucode_in_initrd(void *ucode, size_t size, bool save_patch)

static bool __init load_builtin_amd_microcode(struct cpio_data *cp, int family)
+#ifdef CONFIG_X86_64
char fw_name[36] = "amd-ucode/microcode_amd.bin";

if (family >= 0x15)
@@ -237,6 +238,9 @@ static bool __init load_builtin_amd_microcode(struct cpio_data *cp, int family)
"amd-ucode/microcode_amd_fam%.2xh.bin", family);

return get_builtin_firmware(cp, fw_name);
+ return false;

void __init load_ucode_amd_bsp(int family)
diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
index 10dff3f..b4858d8 100644
--- a/arch/x86/kernel/cpu/microcode/intel_early.c
+++ b/arch/x86/kernel/cpu/microcode/intel_early.c
@@ -523,6 +523,7 @@ EXPORT_SYMBOL_GPL(save_mc_for_early);

static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
+#ifdef CONFIG_X86_64
u32 eax = 0x00000001, ebx, ecx = 0, edx;
int family, model, stepping;
char name[30];
@@ -536,6 +537,9 @@ static bool __init load_builtin_intel_microcode(struct cpio_data *cp)
sprintf(name, "intel-ucode/%02x-%02x-%02x", family, model, stepping);

return get_builtin_firmware(cp, name);
+ return false;

static __initdata char ucode_name[] = "kernel/x86/microcode/GenuineIntel.bin";

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