Transcript: Using the Yocto BSP tools to manage kernel patches and config items
Here's a cut-and-paste shell session showing how to use the Yocto BSP 'yocto-kernel' tool to manage kernel patches and config items for a BSP that was created using 'yocto-bsp'. This particular session uses the qemu ARM BSP that was created in the Transcript: Using the Yocto BSP tools to create a qemu BSP.
The 'yocto-kernel' tool allows you to list, add, and remove kernel patches and individual kernel config items to/from a BSP's kernel recipe.
Like the other Yocto BSP tools, you can get help by simply invoking the command or sub-command with no parameters (first we need to source the environment, again this is using the BSP we created in the session linked to by the above link):
trz@elmorro:/usr/local/dev/Yocto$ source oe-init-build-env
### Shell environment set up for builds. ###
You can now run 'bitbake <target>'
Common targets are:
core-image-minimal
core-image-sato
meta-toolchain
meta-toolchain-sdk
adt-installer
meta-ide-support
You can also run generated qemu images with a command like 'runqemu qemux86'
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel
Usage:
Modify and list Yocto BSP kernel config items and patches.
usage: yocto-kernel [--version] [--help] COMMAND [ARGS]
The most commonly used 'yocto-kernel' commands are:
config list List the modifiable set of bare kernel config options for a BSP
config add Add or modify bare kernel config options for a BSP
config rm Remove bare kernel config options from a BSP
patch list List the patches associated with a BSP
patch add Patch the Yocto kernel for a BSP
patch rm Remove patches from a BSP
See 'yocto-kernel help COMMAND' for more information on a specific command.
Options:
--version show program's version number and exit
-h, --help show this help message and exit
-D, --debug output debug information
Let's start by adding a patch. Here's the patch we'll add: [yocto-testmod.patch: https://wiki.yoctoproject.org/wiki/images/c/c9/Yocto-testmod.patch] NOTE: You should use the patch in the link - scraping the screen from below will result in a patch with whitespace differences that won't apply:
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 6a1a092..b6165b6 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -392,6 +392,11 @@ config HMC6352
This driver provides support for the Honeywell HMC6352 compass,
providing configuration and heading data via sysfs.
+config YOCTO_TESTMOD
+ tristate "Yocto Test Driver"
+ help
+ This driver provides a silly message for testing Yocto.
+
config EP93XX_PWM
tristate "EP93xx PWM support"
depends on ARCH_EP93XX
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 3e1d801..11384d8 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_TI_DAC7512) += ti_dac7512.o
obj-$(CONFIG_C2PORT) += c2port/
obj-$(CONFIG_IWMC3200TOP) += iwmc3200top/
obj-$(CONFIG_HMC6352) += hmc6352.o
+obj-$(CONFIG_YOCTO_TESTMOD) += yocto-testmod.o
obj-y += eeprom/
obj-y += cb710/
obj-$(CONFIG_SPEAR13XX_PCIE_GADGET) += spear13xx_pcie_gadget.o
diff --git a/drivers/misc/yocto-testmod.c b/drivers/misc/yocto-testmod.c
new file mode 100644
index 0000000..81de912
--- /dev/null
+++ b/drivers/misc/yocto-testmod.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2012 Intel Corporation
+ * Authored-by: Tom Zanussi <tom.zanussi@intel.com>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/module.h>
+
+static int __init yocto_testmod_init(void)
+{
+ printk("Kilroy was here! __m_(OuO)_m__");
+}
+
+static void __exit yocto_testmod_exit(void)
+{
+ printk("Kilroy was not here!");
+}
+
+module_init(yocto_testmod_init);
+module_exit(yocto_testmod_exit);
+
+MODULE_AUTHOR("Tom Zanussi <tom.zanussi@intel.com");
+MODULE_DESCRIPTION("Yocto Test Driver");
+MODULE_LICENSE("GPL");
First, let's list the current set of patches associated with the BSP. Again, we'll use the built-in help to remind ourselves of the syntax for that:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch list Usage: List the patches associated with the kernel for a BSP usage: yocto-kernel patch list <bsp-name> This command lists the patches associated with a BSP. NOTE: this only applies to patches listed in the kernel recipe's user-patches.scc file (and currently repeated in its SRC_URI). Options: -h, --help show this help message and exit
The name of our BSP is qemuarm, so we can list the current set of patches like this:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch list myqemuarm The current set of machine-specific patches for myqemuarm is:
As we can see, there are no patches listed, as we'd expect.
Let's see the syntax for adding a patch:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch add Usage: Patch the Yocto kernel for a specific BSP usage: yocto-kernel patch add <bsp-name> [<PATCH> ...] This command adds one or more patches to a BSP's machine branch. The patch will be added to the BSP's linux-yocto kernel user-patches.scc file (and currently repeated in its SRC_URI) and will be guaranteed to be applied in the order specified. Options: -h, --help show this help message and exit
So using the add subcommand as follows, we can add our patch:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch add myqemuarm /home/trz/newpatches/yocto-testmod.patch Added patches: yocto-testmod.patch
Let's verify that the patch was added:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch list myqemuarm The current set of machine-specific patches for myqemuarm is: 1) yocto-testmod.patch
So apparently it was. If you look at the patch, you can see that it adds new code as a module under 'misc devices'. In order to get it built in to the kernel, we need to enable a couple options, one to enable misc devices, and another to enable our particular module.
We can do that using analagous 'yocto-kernel config' subcommands. First, let's see if we already have any BSP-specific config options enabled for our BSP:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config list myqemuarm The current set of machine-specific kernel config items for myqemuarm is: 1) CONFIG_FTRACE_SYSCALLS=y 2) CONFIG_SCHED_TRACER=y 3) CONFIG_IRQSOFF_TRACER=y 4) CONFIG_PREEMPT_TRACER=y
We do - these are a small set of BSP-specific options that were added by the BSP template that generated the BSP.
Let's add to these our two options:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config add myqemuarm CONFIG_MISC_DEVICES=y Added items: CONFIG_MISC_DEVICES=y
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config add myqemuarm CONFIG_YOCTO_TESTMOD=y Added items: CONFIG_YOCTO_TESTMOD=y
Now let's verify that they were added:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config list myqemuarm The current set of machine-specific kernel config items for myqemuarm is: 1) CONFIG_FTRACE_SYSCALLS=y 2) CONFIG_SCHED_TRACER=y 3) CONFIG_IRQSOFF_TRACER=y 4) CONFIG_PREEMPT_TRACER=y 5) CONFIG_MISC_DEVICES=y 6) CONFIG_YOCTO_TESTMOD=y
Now that we've successfully added the patch and associated config items, we can rebuild with the new code and settings, reboot, and we should find our string 'Kilroy was here! __m_(OuO)_m__' in the dmesg log (simply open up a terminal window and type 'dmesg | egrep Kilroy' and you should see the string if everything went as expected).
trz@elmorro:/usr/local/dev/Yocto/build$ bitbake core-image-sato trz@elmorro:/usr/local/dev/Yocto/build$ runqemu qemuarm tmp/deploy/images/zImage-myqemuarm.bin tmp/deploy/images/core-image-sato-myqemuarm.ext3
We can also use 'yocto-kernel' to remove kernel patches and config items. Let's use it to remove the patch and config items we just added.
Let's first remove the patch:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch rm myqemuarm Specify the patches to remove: 1) yocto-testmod.patch 1 Removed patches: yocto-testmod.patch
And let's verify that it was removed:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel patch list myqemuarm The current set of machine-specific patches for myqemuarm is:
Let's do the same for the config items:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config rm myqemuarmSpecify the kernel config items to remove: 1) CONFIG_FTRACE_SYSCALLS=y 2) CONFIG_SCHED_TRACER=y 3) CONFIG_IRQSOFF_TRACER=y 4) CONFIG_PREEMPT_TRACER=y 5) CONFIG_MISC_DEVICES=y 6) CONFIG_YOCTO_TESTMOD=y 5 Removed items: CONFIG_MISC_DEVICES=y trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config rm myqemuarm Specify the kernel config items to remove: 1) CONFIG_FTRACE_SYSCALLS=y 2) CONFIG_SCHED_TRACER=y 3) CONFIG_IRQSOFF_TRACER=y 4) CONFIG_PREEMPT_TRACER=y 5) CONFIG_YOCTO_TESTMOD=y 5 Removed items: CONFIG_YOCTO_TESTMOD=y
And let's also verify that those are now gone:
trz@elmorro:/usr/local/dev/Yocto/build$ yocto-kernel config list myqemuarm The current set of machine-specific kernel config items for myqemuarm is: 1) CONFIG_FTRACE_SYSCALLS=y 2) CONFIG_SCHED_TRACER=y 3) CONFIG_IRQSOFF_TRACER=y 4) CONFIG_PREEMPT_TRACER=y
The appear to be. Rebuilding and booting should show that Kilroy has left (i.e. open a terminal window and typing 'dmesg | egrep Kilroy' should now show nothing again).
