| Message ID | 20210422202452.41704-1-sam.voss@rockwellcollins.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | linux: allow firmware to be included in kernel | expand |
Hello Sam, On Thu, 22 Apr 2021 15:24:52 -0500 Sam Voss <sam.voss@rockwellcollins.com> wrote: > Add functionality to use the kernel's built-in options to allow binary > blobs to be included with the kernel. This is equivalent to the blobs > existing in /lib/firmware, however are available earlier in the boot > process. This may be useful in situations where a device probes before > the rootfs is fully available (such as a squashfs not being loaded > before a usb device probing). > > Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com> Including firmware in the kernel itself has some serious licensing implications: it only works for firmware files that have a license that is compatible with the GPL. If their license is not GPL-compatible, then you cannot redistribute your kernel image. Here is the help text of the corresponding option in the Linux kernel: WARNING: If you include additional firmware files into your binary kernel image that are not available under the terms of the GPL, then it may be a violation of the GPL to distribute the resulting image since it combines both GPL and non-GPL work. You should consult a lawyer of your own before distributing such an image. I am not a lawyer, but I think the wording is a bit unfortunate: I think if the firmware is under a license that is compatible with the GPL, it is fine. But if it has a non GPL-compatible license, it's a no-go. So I would be OK to include this, but with the appropriate warning in the Buildroot options. Best regards, Thomas
Hey Thomas, On Thu, Apr 22, 2021 at 3:55 PM Thomas Petazzoni <thomas.petazzoni@bootlin.com> wrote: > > Hello Sam, > > On Thu, 22 Apr 2021 15:24:52 -0500 > Sam Voss <sam.voss@rockwellcollins.com> wrote: > > > Add functionality to use the kernel's built-in options to allow binary > > blobs to be included with the kernel. This is equivalent to the blobs > > existing in /lib/firmware, however are available earlier in the boot > > process. This may be useful in situations where a device probes before > > the rootfs is fully available (such as a squashfs not being loaded > > before a usb device probing). > > > > Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com> > > Including firmware in the kernel itself has some serious licensing > implications: it only works for firmware files that have a license that > is compatible with the GPL. If their license is not GPL-compatible, > then you cannot redistribute your kernel image. > > Here is the help text of the corresponding option in the Linux kernel: > > WARNING: If you include additional firmware files into your binary > kernel image that are not available under the terms of the GPL, > then it may be a violation of the GPL to distribute the resulting > image since it combines both GPL and non-GPL work. You should > consult a lawyer of your own before distributing such an image. > > I am not a lawyer, but I think the wording is a bit unfortunate: I > think if the firmware is under a license that is compatible with the > GPL, it is fine. But if it has a non GPL-compatible license, it's a > no-go. I completely agree with everything you said here - I had investigated (based on the kernels warning text) my use case, but had not considered wanting to propagate that warning out into the buildroot option as well > > So I would be OK to include this, but with the appropriate warning in > the Buildroot options. I'll add that warning and send a v2 here momentarily. Thanks for the quick review,
diff --git a/linux/Config.in b/linux/Config.in index 2460c3f124..ef0d9f79ea 100644 --- a/linux/Config.in +++ b/linux/Config.in @@ -479,6 +479,19 @@ config BR2_LINUX_KERNEL_NEEDS_HOST_LIBELF CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". +config BR2_LINUX_KERNEL_EXTRA_FIRMWARE + bool "Build firmware binaries into the kernel" + help + Include the firmware from linux-firmware into the kernel + using the CONFIG_EXTRA_FIRMWARE option. + +config BR2_LINUX_KERNEL_EXTRA_FIRMWARE_BINARIES + string "External firmware blobs to build into the kernel binary" + depends on BR2_LINUX_KERNEL_EXTRA_FIRMWARE + help + Space delimited list of firmware to be built into the kernel. + These files must exist in the target's /lib/firmware. + # Linux extensions source "linux/Config.ext.in" diff --git a/linux/linux.mk b/linux/linux.mk index b67f739ca0..d581dd7f5d 100644 --- a/linux/linux.mk +++ b/linux/linux.mk @@ -78,7 +78,8 @@ LINUX_MAKE_ENV = \ LINUX_INSTALL_IMAGES = YES LINUX_DEPENDENCIES += host-kmod \ - $(if $(BR2_PACKAGE_INTEL_MICROCODE),intel-microcode) + $(if $(BR2_PACKAGE_INTEL_MICROCODE),intel-microcode) \ + $(if $(BR2_LINUX_KERNEL_EXTRA_FIRMWARE),linux-firmware) # Starting with 4.16, the generated kconfig paser code is no longer # shipped with the kernel sources, so we need flex and bison, but @@ -384,6 +385,10 @@ define LINUX_KCONFIG_FIXUP_CMDS $(call KCONFIG_ENABLE_OPT,CONFIG_FB) $(call KCONFIG_ENABLE_OPT,CONFIG_LOGO) $(call KCONFIG_ENABLE_OPT,CONFIG_LOGO_LINUX_CLUT224)) + $(if $(BR2_LINUX_KERNEL_EXTRA_FIRMWARE), + $(call KCONFIG_ENABLE_OPT,CONFIG_FIRMWARE_IN_KERNEL) + $(call KCONFIG_SET_OPT,CONFIG_EXTRA_FIRMWARE,$(BR2_LINUX_KERNEL_EXTRA_FIRMWARE_BINARIES)) + $(call KCONFIG_SET_OPT,CONFIG_EXTRA_FIRMWARE_DIR,"$(TARGET_DIR)/lib/firmware")) $(call KCONFIG_DISABLE_OPT,CONFIG_GCC_PLUGINS) $(PACKAGES_LINUX_CONFIG_FIXUPS)
Add functionality to use the kernel's built-in options to allow binary blobs to be included with the kernel. This is equivalent to the blobs existing in /lib/firmware, however are available earlier in the boot process. This may be useful in situations where a device probes before the rootfs is fully available (such as a squashfs not being loaded before a usb device probing). Signed-off-by: Sam Voss <sam.voss@rockwellcollins.com> --- linux/Config.in | 13 +++++++++++++ linux/linux.mk | 7 ++++++- 2 files changed, 19 insertions(+), 1 deletion(-)