From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yann E. MORIN Date: Fri, 25 Sep 2020 09:37:58 +0200 Subject: [Buildroot] [PATCH 1/2] linux: show compression options only on some architectures In-Reply-To: <20200924122222.3449188-1-thomas.petazzoni@bootlin.com> References: <20200924122222.3449188-1-thomas.petazzoni@bootlin.com> Message-ID: <20200925073758.GD11621@scaer> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Thomas, All, On 2020-09-24 14:22 +0200, Thomas Petazzoni spake thusly: > Our Linux kernel compression options have the effect of enabling > CONFIG_KERNEL_{GZIP,LZMA,LZ4,...}. However, those configuration > options only exist on a subset of the CPU architectures, and it is > confusing to have such a choice visible when it in fact has no > effect. For example on ARM64, it has absolutely no effect, and the way > to create a compressed image is different, and the image is not > self-extractible. > > So, we introduce a BR2_LINUX_KERNEL_ARCH_HAS_COMPRESSION to know which > architectures have compression support. Of course, it's never going to > be perfect as the set of architectures supporting compression might > change over time. But at least, it will allow us to hide this option > on architectures that do not at this point support compression. > > Signed-off-by: Thomas Petazzoni > --- > linux/Config.in | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/linux/Config.in b/linux/Config.in > index 49da2b81b2..9f2af6da5b 100644 > --- a/linux/Config.in > +++ b/linux/Config.in > @@ -299,6 +299,22 @@ endchoice > # Kernel compression format > # > > +# Indicates whether this architecture has support for built-in kernel > +# compression, i.e architectures that select one of > +# HAVE_KERNEL_{GZIP,LZMA,LZ4,LZO,XZ,UNCOMPRESSED} > +config BR2_LINUX_KERNEL_ARCH_HAS_COMPRESSION > + bool > + default y if BR2_arcle || BR2_arceb > + default y if BR2_arm || BR2_armeb > + default y if BR2_csky > + default y if BR2_i386 > + default y if BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el > + default y if BR2_powerpc || BR2_powerpc64 || BR2_powerpc64le > + default y if BR2_sh > + default y if BR2_x86_64 > + > +if BR2_LINUX_KERNEL_ARCH_HAS_COMPRESSION So, if the arch does not support kernel image compression, we will have none of the compression symbols defined, which means that, in linux.mk, we would have: 104 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_GZIP) += CONFIG_KERNEL_GZIP 105 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZ4) += CONFIG_KERNEL_LZ4 106 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZMA) += CONFIG_KERNEL_LZMA 107 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZO) += CONFIG_KERNEL_LZO 108 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_XZ) += CONFIG_KERNEL_XZ 109 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_ZSTD) += CONFIG_KERNEL_ZSTD [--SNIP--] 319 define LINUX_KCONFIG_FIXUP_CMDS 322 $(call KCONFIG_ENABLE_OPT,$(strip $(LINUX_COMPRESSION_OPT_y))) But then, LINUX_COMPRESSION_OPT_y would be empty, so we'd call KCONFIG_ENABLE_OPT with an empty string, which would expand to: $(call KCONFIG_MUNGE_DOT_CONFIG, $(1), $(1)=y, $(2)) ... and replacing the parameters would give (I'm pretty sure you'll see where we're going now): $(call KCONFIG_MUNGE_DOT_CONFIG, , =y, $(2)) When KCONFIG_MUNGE_DOT_CONFIG is expanded, we'd get: $(SED) "/\\<$(strip $(1))\\>/d" $(call KCONFIG_DOT_CONFIG,$(3)) echo '$(strip $(2))' >> $(call KCONFIG_DOT_CONFIG,$(3)) ... which would eventualy lead us to: $(SED) "/\\<)\\>/d" /some/.config-file echo '=y' >> /some/.config-file And to be honest, I am not sure that last line would generate a fully legit kconfig setting... ;-) Of course, running 'make oldconfig' on that modified .config would drop invalid lines, so you would not notivce the issue, but still this is not correct... Regards, Yann E. MORIN. > choice > prompt "Kernel compression format" > help > @@ -326,6 +342,8 @@ config BR2_LINUX_KERNEL_ZSTD > > endchoice > > +endif > + > config BR2_LINUX_KERNEL_IMAGE_TARGET_NAME > string "Kernel image target name" > depends on BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM > -- > 2.26.2 > > _______________________________________________ > buildroot mailing list > buildroot at busybox.net > http://lists.busybox.net/mailman/listinfo/buildroot -- .-----------------.--------------------.------------------.--------------------. | Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | | +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ | | +33 561 099 427 `------------.-------: X AGAINST | \e/ There is no | | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. | '------------------------------^-------^------------------^--------------------'