linux-kernel - [PATCH 02/21] ARM: default machine descriptor for multiplatform

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1366910944-3033663-3-git-send-email-arnd@arndb.de>
Date:	Thu, 25 Apr 2013 19:28:45 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
	"Russell King - ARM Linux" <linux@....linux.org.uk>,
	Rob Herring <robherring2@...il.com>
Subject: [PATCH 02/21] ARM: default machine descriptor for multiplatform

Since we now have default implementations for init_time and init_irq,
the init_machine callback is the only one that is not yet optional,
but since simple DT based platforms all have the same
of_platform_populate function call in there, we can consolidate them
as well, and then actually boot with a completely empty machine_desc.
Unofortunately we cannot just default to an empty init_machine: We
cannot call of_platform_populate before init_machine because that
does not work in case of auxdata, and we cannot call it after
init_machine either because the machine might need to run code
after adding the devices.

To take the final step, this adds support for booting without defining
any machine_desc whatsoever.

For the case that CONFIG_MULTIPLATFORM is enabled, it adds a
global machine descriptor that never matches any machine but is
used as a fallback if nothing else matches. We assume that without
CONFIG_MULTIPLATFORM, we only want to boot on the systems that the kernel
is built for, so we still retain the build-time warning for missing
machine descriptors and the run-time warning when the platform does not
match in that case.

In the case that we run on a multiplatform kernel and the machine
provides a fully populated device tree, we attempt to keep booting,
hoping that no machine specific callbacks are necessary.

Finally, this also removes the misguided "select ARCH_VEXPRESS" that
was only added to avoid a build error for allnoconfig kernels.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Nicolas Pitre <nico@...aro.org>
Acked-by: Olof Johansson <olof@...om.net>
Cc: "Russell King - ARM Linux" <linux@....linux.org.uk>
Cc: Rob Herring <robherring2@...il.com>
---
 arch/arm/Kconfig          |  1 -
 arch/arm/kernel/devtree.c |  7 +++++++
 arch/arm/kernel/setup.c   | 11 ++++++++++-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a0d58a6..8c33760 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -890,7 +890,6 @@ config ARCH_MULTI_V7
 	bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)"
 	default y
 	select ARCH_MULTI_V6_V7
-	select ARCH_VEXPRESS
 	select CPU_V7

 config ARCH_MULTI_V6_V7
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 70f1bde..5af04f6 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -180,6 +180,13 @@ struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
 	unsigned long dt_root;
 	const char *model;

+#ifdef CONFIG_ARCH_MULTIPLATFORM
+	DT_MACHINE_START(GENERIC_DT, "Generic DT based system")
+	MACHINE_END
+
+	mdesc_best = (struct machine_desc *)&__mach_desc_GENERIC_DT;
+#endif
+
 	if (!dt_phys)
 		return NULL;

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 408f446..d039623 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -18,6 +18,7 @@
 #include <linux/bootmem.h>
 #include <linux/seq_file.h>
 #include <linux/screen_info.h>
+#include <linux/of_platform.h>
 #include <linux/init.h>
 #include <linux/kexec.h>
 #include <linux/of_fdt.h>
@@ -672,9 +673,17 @@ struct screen_info screen_info = {

 static int __init customize_machine(void)
 {
-	/* customizes platform devices, or adds new ones */
+	/*
+	 * customizes platform devices, or adds new ones
+	 * On DT based machines, we fall back to populating the
+	 * machine from the device tree, if no callback is provided,
+	 * otherwise we would always need an init_machine callback.
+	 */
 	if (machine_desc->init_machine)
 		machine_desc->init_machine();
+	else
+		of_platform_populate(NULL, of_default_bus_match_table,
+					NULL, NULL);
 	return 0;
 }
 arch_initcall(customize_machine);
-- 
1.8.1.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/