On 2014/9/10 0:26, Catalin Marinas wrote:

On Mon, Sep 01, 2014 at 03:57:40PM +0100, Hanjun Guo wrote:

quoted

diff --git a/arch/arm64/include/asm/acenv.h b/arch/arm64/include/asm/acenv.h
new file mode 100644
index 0000000..3899ee6
--- /dev/null
+++ b/arch/arm64/include/asm/acenv.h

@@ -0,0 +1,18 @@
+/*
+ * ARM64 specific ACPICA environments and implementation
+ *
+ * Copyright (C) 2014, Linaro Ltd.
+ *   Author: Hanjun Guo <hanjun.guo@linaro.org>
+ *   Author: Graeme Gregory <graeme.gregory@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_ACENV_H
+#define _ASM_ACENV_H
+
+#define ACPI_FLUSH_CPU_CACHE() WARN_ONCE(1, "Not currently supported on ARM64")

Does this mean that it will be supported at some point? Looking at the
places where this function is called, I don't really see how this would
ever work on ARM. Which means that we add such macro just to be able to
compile code that would never be used on arm64. I would rather see the
relevant ACPI files only compiled on x86/IA-64 rather than arm64.

quoted

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
new file mode 100644
index 0000000..9252f72
--- /dev/null
+++ b/arch/arm64/kernel/acpi.c

[...]

quoted

+/*
+ * acpi_boot_table_init() called from setup_arch(), always.
+ *	1. find RSDP and get its address, and then find XSDT
+ *	2. extract all tables and checksums them all
+ *
+ * We can parse ACPI boot-time tables such as MADT after
+ * this function is called.
+ */
+void __init acpi_boot_table_init(void)
+{
+	/* If acpi_disabled, bail out */
+	if (acpi_disabled)
+		return;

So at this point, there wouldn't be anything yet to set acpi_disabled to
1, unless !CONFIG_ACPI.

quoted

+
+	/* Initialize the ACPI boot-time table parser. */
+	if (acpi_table_init())
+		disable_acpi();

Do you need anything more to add to this function later? Otherwise, just
call it in setup_arch() directly (maybe dependent on
IS_ENABLED(CONFIG_ACPI) or just create an equivalent dummy
acpi_table_init() when not configured).

We add FADT parse function to this function later.

quoted

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index c96172a..fb7cc0e 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c

@@ -43,6 +43,7 @@
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 #include <linux/efi.h>
+#include <linux/acpi.h>
 
 #include <asm/fixmap.h>
 #include <asm/cpu.h>

@@ -385,6 +386,9 @@ void __init setup_arch(char **cmdline_p)
 	efi_init();
 	arm64_memblock_init();
 
+	/* Parse the ACPI tables for possible boot-time configuration */
+	acpi_boot_table_init();

Is there any dummy acpi_boot_table_init() when !CONFIG_ACPI? I couldn't
see one in this patch, so I don't see how this would compile when ACPI
is disabled.

There is a stub function in linux/acpi.h when ACPI is disabled.

Thanks
Hanjun