| Message ID | 20200407155352.16617-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kbuild: add dummy toolchains to enable all cc-option etc. in Kconfig | expand |
On Wed, Apr 08, 2020 at 12:53:52AM +0900, Masahiro Yamada wrote: > Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG > options your compiler does not support. This works well if you configure > and build the kernel on the same host machine. > > It is inconvenient if you prepare the .config that is carried to a > different build environment (typically this happens when you package > the kernel for distros) because using a different compiler potentially > produces different CONFIG options than the real build environment. > So, you probably want to make as many options visible as possible. > In other words, you need to create a super-set of CONFIG options that > cover any build environment. If some of the CONFIG options turned out > to be unsupported on the build machine, they are automatically disabled > by the nature of Kconfig. > > However, it is not feasible to get a full-featured compiler for every > arch. > > This issue was discussed here: > > https://lkml.org/lkml/2019/12/9/620 > > Other than distros, savedefconfig is also a problem. Some arch sub-systems > periodically resync defconfig files. If you use a less-capable compiler > for savedefconfig, options that do not meet 'depends on $(cc-option,...)' > will be forcibly disabled. So, 'make defconfig && make savedefconfig' > may silently change the behavior. > > This commit adds a set of dummy toolchains that pretend to support any > feature. > > Most of compiler features are tested by cc-option, which simply checks > the exit code of $(CC). The dummy tools are shell scripts that always > exit with 0. So, $(cc-option, ...) is evaluated as 'y'. > > There are more complicated checks such as: > > scripts/gcc-x86_{32,64}-has-stack-protector.sh > scripts/gcc-plugin.sh > scripts/tools-support-relr.sh > > scripts/dummy-tools/gcc passes all checks. > > From the top directory of the source tree, you can do: > > $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > Reviewed-by: Philipp Rudo <prudo@linux.ibm.com> > --- > > Changes in v2: > - support --version and -v for ld, objdump, nm Great, "make ARCH=powerpc CROSS_COMPILE=scripts/dummy-tools/ help" no longer spits out "/bin/sh: line 0: [: -ge: unary operator expected" and everything looks to work as expected. Tested-by: Jeremy Cline <jcline@redhat.com> > > scripts/dummy-tools/gcc | 91 +++++++++++++++++++++++++++++++++++++ > scripts/dummy-tools/ld | 30 ++++++++++++ > scripts/dummy-tools/nm | 1 + > scripts/dummy-tools/objcopy | 1 + > 4 files changed, 123 insertions(+) > create mode 100755 scripts/dummy-tools/gcc > create mode 100755 scripts/dummy-tools/ld > create mode 120000 scripts/dummy-tools/nm > create mode 120000 scripts/dummy-tools/objcopy > > diff --git a/scripts/dummy-tools/gcc b/scripts/dummy-tools/gcc > new file mode 100755 > index 000000000000..33487e99d83e > --- /dev/null > +++ b/scripts/dummy-tools/gcc > @@ -0,0 +1,91 @@ > +#!/bin/sh > +# SPDX-License-Identifier: GPL-2.0-only > +# > +# Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG > +# options your compiler does not support. This works well if you configure and > +# build the kernel on the same host machine. > +# > +# It is inconvenient if you prepare the .config that is carried to a different > +# build environment (typically this happens when you package the kernel for > +# distros) because using a different compiler potentially produces different > +# CONFIG options than the real build environment. So, you probably want to make > +# as many options visible as possible. In other words, you need to create a > +# super-set of CONFIG options that cover any build environment. If some of the > +# CONFIG options turned out to be unsupported on the build machine, they are > +# automatically disabled by the nature of Kconfig. > +# > +# However, it is not feasible to get a full-featured compiler for every arch. > +# Hence these dummy toolchains to make all compiler tests pass. > +# > +# Usage: > +# > +# From the top directory of the source tree, run > +# > +# $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig > +# > +# Most of compiler features are tested by cc-option, which simply checks the > +# exit code of $(CC). This script does nothing and just exits with 0 in most > +# cases. So, $(cc-option, ...) is evaluated as 'y'. > +# > +# This scripts caters to more checks; handle --version and pre-process __GNUC__ > +# etc. to pretend to be GCC, and also do right things to satisfy some scripts. > + > +# Check if the first parameter appears in the rest. Succeeds if found. > +# This helper is useful if a particular option was passed to this script. > +# Typically used like this: > +# arg_contain <word-you-are-searching-for> "$@" > +arg_contain () > +{ > + search="$1" > + shift > + > + while [ $# -gt 0 ] > + do > + if [ "$search" = "$1" ]; then > + return 0 > + fi > + shift > + done > + > + return 1 > +} > + > +# To set CONFIG_CC_IS_GCC=y > +if arg_contain --version "$@"; then > + echo "gcc (scripts/dummy-tools/gcc)" > + exit 0 > +fi > + > +if arg_contain -E "$@"; then > + # For scripts/gcc-version.sh; This emulates GCC 20.0.0 > + if arg_contain - "$@"; then > + sed 's/^__GNUC__$/20/; s/^__GNUC_MINOR__$/0/; s/^__GNUC_PATCHLEVEL__$/0/' > + exit 0 > + else > + echo "no input files" >&2 > + exit 1 > + fi > +fi > + > +if arg_contain -S "$@"; then > + # For scripts/gcc-x86-*-has-stack-protector.sh > + if arg_contain -fstack-protector "$@"; then > + echo "%gs" > + exit 0 > + fi > +fi > + > +# For scripts/gcc-plugin.sh > +if arg_contain -print-file-name=plugin "$@"; then > + plugin_dir=$(mktemp -d) > + > + sed -n 's/.*#include "\(.*\)"/\1/p' $(dirname $0)/../gcc-plugins/gcc-common.h | > + while read header > + do > + mkdir -p $plugin_dir/include/$(dirname $header) > + touch $plugin_dir/include/$header > + done > + > + echo $plugin_dir > + exit 0 > +fi > diff --git a/scripts/dummy-tools/ld b/scripts/dummy-tools/ld > new file mode 100755 > index 000000000000..f68233050405 > --- /dev/null > +++ b/scripts/dummy-tools/ld > @@ -0,0 +1,30 @@ > +#!/bin/sh > +# SPDX-License-Identifier: GPL-2.0-only > + > +# Dummy script that always succeeds. > + > +# Check if the first parameter appears in the rest. Succeeds if found. > +# This helper is useful if a particular option was passed to this script. > +# Typically used like this: > +# arg_contain <word-you-are-searching-for> "$@" > +arg_contain () > +{ > + search="$1" > + shift > + > + while [ $# -gt 0 ] > + do > + if [ "$search" = "$1" ]; then > + return 0 > + fi > + shift > + done > + > + return 1 > +} > + > +if arg_contain --version "$@" || arg_contain -v "$@"; then > + progname=$(basename $0) > + echo "GNU $progname (scripts/dummy-tools/$progname) 2.50" > + exit 0 > +fi > diff --git a/scripts/dummy-tools/nm b/scripts/dummy-tools/nm > new file mode 120000 > index 000000000000..c0648b38dd42 > --- /dev/null > +++ b/scripts/dummy-tools/nm > @@ -0,0 +1 @@ > +ld > \ No newline at end of file > diff --git a/scripts/dummy-tools/objcopy b/scripts/dummy-tools/objcopy > new file mode 120000 > index 000000000000..c0648b38dd42 > --- /dev/null > +++ b/scripts/dummy-tools/objcopy > @@ -0,0 +1 @@ > +ld > \ No newline at end of file > -- > 2.17.1 >
diff --git a/scripts/dummy-tools/gcc b/scripts/dummy-tools/gcc new file mode 100755 index 000000000000..33487e99d83e --- /dev/null +++ b/scripts/dummy-tools/gcc @@ -0,0 +1,91 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only +# +# Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG +# options your compiler does not support. This works well if you configure and +# build the kernel on the same host machine. +# +# It is inconvenient if you prepare the .config that is carried to a different +# build environment (typically this happens when you package the kernel for +# distros) because using a different compiler potentially produces different +# CONFIG options than the real build environment. So, you probably want to make +# as many options visible as possible. In other words, you need to create a +# super-set of CONFIG options that cover any build environment. If some of the +# CONFIG options turned out to be unsupported on the build machine, they are +# automatically disabled by the nature of Kconfig. +# +# However, it is not feasible to get a full-featured compiler for every arch. +# Hence these dummy toolchains to make all compiler tests pass. +# +# Usage: +# +# From the top directory of the source tree, run +# +# $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig +# +# Most of compiler features are tested by cc-option, which simply checks the +# exit code of $(CC). This script does nothing and just exits with 0 in most +# cases. So, $(cc-option, ...) is evaluated as 'y'. +# +# This scripts caters to more checks; handle --version and pre-process __GNUC__ +# etc. to pretend to be GCC, and also do right things to satisfy some scripts. + +# Check if the first parameter appears in the rest. Succeeds if found. +# This helper is useful if a particular option was passed to this script. +# Typically used like this: +# arg_contain <word-you-are-searching-for> "$@" +arg_contain () +{ + search="$1" + shift + + while [ $# -gt 0 ] + do + if [ "$search" = "$1" ]; then + return 0 + fi + shift + done + + return 1 +} + +# To set CONFIG_CC_IS_GCC=y +if arg_contain --version "$@"; then + echo "gcc (scripts/dummy-tools/gcc)" + exit 0 +fi + +if arg_contain -E "$@"; then + # For scripts/gcc-version.sh; This emulates GCC 20.0.0 + if arg_contain - "$@"; then + sed 's/^__GNUC__$/20/; s/^__GNUC_MINOR__$/0/; s/^__GNUC_PATCHLEVEL__$/0/' + exit 0 + else + echo "no input files" >&2 + exit 1 + fi +fi + +if arg_contain -S "$@"; then + # For scripts/gcc-x86-*-has-stack-protector.sh + if arg_contain -fstack-protector "$@"; then + echo "%gs" + exit 0 + fi +fi + +# For scripts/gcc-plugin.sh +if arg_contain -print-file-name=plugin "$@"; then + plugin_dir=$(mktemp -d) + + sed -n 's/.*#include "\(.*\)"/\1/p' $(dirname $0)/../gcc-plugins/gcc-common.h | + while read header + do + mkdir -p $plugin_dir/include/$(dirname $header) + touch $plugin_dir/include/$header + done + + echo $plugin_dir + exit 0 +fi diff --git a/scripts/dummy-tools/ld b/scripts/dummy-tools/ld new file mode 100755 index 000000000000..f68233050405 --- /dev/null +++ b/scripts/dummy-tools/ld @@ -0,0 +1,30 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only + +# Dummy script that always succeeds. + +# Check if the first parameter appears in the rest. Succeeds if found. +# This helper is useful if a particular option was passed to this script. +# Typically used like this: +# arg_contain <word-you-are-searching-for> "$@" +arg_contain () +{ + search="$1" + shift + + while [ $# -gt 0 ] + do + if [ "$search" = "$1" ]; then + return 0 + fi + shift + done + + return 1 +} + +if arg_contain --version "$@" || arg_contain -v "$@"; then + progname=$(basename $0) + echo "GNU $progname (scripts/dummy-tools/$progname) 2.50" + exit 0 +fi diff --git a/scripts/dummy-tools/nm b/scripts/dummy-tools/nm new file mode 120000 index 000000000000..c0648b38dd42 --- /dev/null +++ b/scripts/dummy-tools/nm @@ -0,0 +1 @@ +ld \ No newline at end of file diff --git a/scripts/dummy-tools/objcopy b/scripts/dummy-tools/objcopy new file mode 120000 index 000000000000..c0648b38dd42 --- /dev/null +++ b/scripts/dummy-tools/objcopy @@ -0,0 +1 @@ +ld \ No newline at end of file
Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG options your compiler does not support. This works well if you configure and build the kernel on the same host machine. It is inconvenient if you prepare the .config that is carried to a different build environment (typically this happens when you package the kernel for distros) because using a different compiler potentially produces different CONFIG options than the real build environment. So, you probably want to make as many options visible as possible. In other words, you need to create a super-set of CONFIG options that cover any build environment. If some of the CONFIG options turned out to be unsupported on the build machine, they are automatically disabled by the nature of Kconfig. However, it is not feasible to get a full-featured compiler for every arch. This issue was discussed here: https://lkml.org/lkml/2019/12/9/620 Other than distros, savedefconfig is also a problem. Some arch sub-systems periodically resync defconfig files. If you use a less-capable compiler for savedefconfig, options that do not meet 'depends on $(cc-option,...)' will be forcibly disabled. So, 'make defconfig && make savedefconfig' may silently change the behavior. This commit adds a set of dummy toolchains that pretend to support any feature. Most of compiler features are tested by cc-option, which simply checks the exit code of $(CC). The dummy tools are shell scripts that always exit with 0. So, $(cc-option, ...) is evaluated as 'y'. There are more complicated checks such as: scripts/gcc-x86_{32,64}-has-stack-protector.sh scripts/gcc-plugin.sh scripts/tools-support-relr.sh scripts/dummy-tools/gcc passes all checks. From the top directory of the source tree, you can do: $ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Philipp Rudo <prudo@linux.ibm.com> --- Changes in v2: - support --version and -v for ld, objdump, nm scripts/dummy-tools/gcc | 91 +++++++++++++++++++++++++++++++++++++ scripts/dummy-tools/ld | 30 ++++++++++++ scripts/dummy-tools/nm | 1 + scripts/dummy-tools/objcopy | 1 + 4 files changed, 123 insertions(+) create mode 100755 scripts/dummy-tools/gcc create mode 100755 scripts/dummy-tools/ld create mode 120000 scripts/dummy-tools/nm create mode 120000 scripts/dummy-tools/objcopy