Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On Thu, Mar 4, 2021 at 8:07 AM Fangrui Song wrote:
>
>
> On 2021-03-03, Masahiro Yamada wrote:
> >Hi.
> >
> >On Wed, Mar 3, 2021 at 6:44 AM Fangrui Song wrote:
> >>
> >> Reviewed-by: Fangrui Song
> >>
> >> Thanks for the clean-up!
> >> --gcc-toolchain= is an obsscure way searching for GCC installation
> >> prefixes (--prefix).
> >> The logic is complex and different for different
> >> distributions/architectures.
> >>
> >> If we specify --prefix= (-B) explicitly, --gcc-toolchain is not needed.
> >
> >
> >I tested this, and worked for me too.
> >
> >Before applying this patch, could you please
> >help me understand the logic?
> >
> >
> >
> >
> >I checked the manual
> >(https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-b-dir)
> >
> >
> >
> >-B, --prefix , --prefix=
> >Add to search path for binaries and object files used implicitly
> >
> >--gcc-toolchain=, -gcc-toolchain
> >Use the gcc toolchain at the given directory
> >
> >
> >Hmm, this description is too concise
> >to understand how it works...
> >
> >
> >
> >I use Ubuntu 20.10.
> >
> >I use distro's default clang
> >located in /usr/bin/clang.
> >
> >I place my aarch64 linaro toolchain in
> >/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu-gcc,
> >which is not in my PATH environment.
> >
> >
> >
> >
> >From my some experiments,
> >
> >clang --target=aarch64-linux-gnu -no-integrated-as \
> >--prefix=/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu- ...
> >
> >works almost equivalent to
> >
> >PATH=/home/masahiro/tools/aarch64-linaro-7.5/bin:$PATH \
> >clang --target=aarch64-linux-gnu -no-integrated-as ...
> >
> >
> >Then, clang will pick up aarch64-linux-gnu-as
> >found in the search path.
> >
> >Is this correct?
> >
> >
> >On the other hand, I could not understand
> >what the purpose of --gcc-toolchain= is.
> >
> >
> >Even if I add --gcc-toolchain=/home/masahiro/tools/aarch64-linaro-7.5,
> >it does not make any difference, and it is completely useless.
> >
> >
> >I read the comment from stephenhines:
> >https://github.com/ClangBuiltLinux/linux/issues/78
> >
> >How could --gcc-toolchain be used
> >in a useful way?
>
> --gcc-toolchain was introduced in
> https://reviews.llvm.org/rG1af7c219c7113a35415651127f05cdf056b63110
> to provide a flexible alternative to autoconf configure-time
> --with-gcc-toolchain (now cmake variable GCC_INSTALL_PREFIX).
>
> I agree the option is confusing, the documentation is poor, and probably very
> few people understand what it does.
> I apologize that my previous reply is not particular correct.
> So the more correct answer is below:
>
>
> A --prefix option can specify either of
>
> 1) A directory (for something like /a/b/lib/gcc/arm-linux-androideabi, this
> should be /a/b, the parent directory of 'lib')
> 2) A path fragment like /usr/bin/aarch64-linux-gnu-
>
> The directory values of the --prefix list and --gcc-toolchain are used to
> detect GCC installation directories. The directory is used to fetch include
> directories, system library directories and binutils directories (as,
> objcopy).
> (See below, Linux kernel only needs the binutils executables, so the
> include/library logic is really useless to us)
>
> The logic is around
> https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/Gnu.cpp#L1910
>
>Prefixes = --prefix/-B list (only the directory subset is effective)
>StringRef GCCToolchainDir = --gcc-toolchain= or CMake variable
> GCC_INSTALL_PREFIX
>if (GCCToolchainDir != "") {
> Prefixes.push_back(std::string(GCCToolchainDir));
>} else {
> if (!D.SysRoot.empty()) {
>Prefixes.push_back(D.SysRoot);
>// Add D.SysRoot+"/usr" to Prefixes. Some distributions add more
> directories.
>AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
> }
>
> // D.InstalledDir is the directory of the clang executable, e.g. /usr/bin
> Prefixes.push_back(D.InstalledDir + "/..");
>
> if (D.SysRoot.empty())
>AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
>}
>
>// Gentoo / ChromeOS specific logic.
>// I think this block is misplaced.
>if (GCCToolchainDir == "" || GCCToolchainDir == D.SysRoot + "/usr") {
> ...
>}
>
>// Loop over the various components which exist and select the best GCC
>// installation available. GCC installs are ranked by version number.
>Version = GCCVersion::Parse("0.0.0");
>for (const std::string : Prefixes) {
> auto = D.getVFS();
> if (!VFS.exists(Prefix))
>continue;
>
> // CandidateLibDirs is a subset of {/lib64, /lib32, /lib}.
> for (StringRef Suffix : CandidateLibDirs) {
>const std::string LibDir = Prefix + Suffix.str();
>if (!VFS.exists(LibDir))
> continue;
>bool GCCDirExists = VFS.exists(LibDir + "/gcc");
>bool GCCCrossDirExists = VFS.exists(LibDir + "/gcc-cross");
>
>// Precise match. Detect
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On Wed, Mar 3, 2021 at 3:07 PM Fangrui Song wrote:
>
>
> On 2021-03-03, Masahiro Yamada wrote:
> >Hi.
> >
> >On Wed, Mar 3, 2021 at 6:44 AM Fangrui Song wrote:
> >>
> >> Reviewed-by: Fangrui Song
> >>
> >> Thanks for the clean-up!
> >> --gcc-toolchain= is an obsscure way searching for GCC installation
> >> prefixes (--prefix).
> >> The logic is complex and different for different
> >> distributions/architectures.
> >>
> >> If we specify --prefix= (-B) explicitly, --gcc-toolchain is not needed.
> >
> >
> >I tested this, and worked for me too.
> >
> >Before applying this patch, could you please
> >help me understand the logic?
> >
> >
> >
> >
> >I checked the manual
> >(https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-b-dir)
> >
> >
> >
> >-B, --prefix , --prefix=
> >Add to search path for binaries and object files used implicitly
> >
> >--gcc-toolchain=, -gcc-toolchain
> >Use the gcc toolchain at the given directory
> >
> >
> >Hmm, this description is too concise
> >to understand how it works...
> >
> >
> >
> >I use Ubuntu 20.10.
> >
> >I use distro's default clang
> >located in /usr/bin/clang.
> >
> >I place my aarch64 linaro toolchain in
> >/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu-gcc,
> >which is not in my PATH environment.
> >
> >
> >
> >
> >From my some experiments,
> >
> >clang --target=aarch64-linux-gnu -no-integrated-as \
> >--prefix=/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu- ...
> >
> >works almost equivalent to
> >
> >PATH=/home/masahiro/tools/aarch64-linaro-7.5/bin:$PATH \
> >clang --target=aarch64-linux-gnu -no-integrated-as ...
> >
> >
> >Then, clang will pick up aarch64-linux-gnu-as
> >found in the search path.
> >
> >Is this correct?
> >
> >
> >On the other hand, I could not understand
> >what the purpose of --gcc-toolchain= is.
> >
> >
> >Even if I add --gcc-toolchain=/home/masahiro/tools/aarch64-linaro-7.5,
> >it does not make any difference, and it is completely useless.
> >
> >
> >I read the comment from stephenhines:
> >https://github.com/ClangBuiltLinux/linux/issues/78
> >
> >How could --gcc-toolchain be used
> >in a useful way?
>
> --gcc-toolchain was introduced in
> https://reviews.llvm.org/rG1af7c219c7113a35415651127f05cdf056b63110
> to provide a flexible alternative to autoconf configure-time
> --with-gcc-toolchain (now cmake variable GCC_INSTALL_PREFIX).
>
> I agree the option is confusing, the documentation is poor, and probably very
> few people understand what it does.
> I apologize that my previous reply is not particular correct.
> So the more correct answer is below:
>
>
> A --prefix option can specify either of
>
> 1) A directory (for something like /a/b/lib/gcc/arm-linux-androideabi, this
> should be /a/b, the parent directory of 'lib')
> 2) A path fragment like /usr/bin/aarch64-linux-gnu-
>
> The directory values of the --prefix list and --gcc-toolchain are used to
> detect GCC installation directories. The directory is used to fetch include
> directories, system library directories and binutils directories (as,
> objcopy).
> (See below, Linux kernel only needs the binutils executables, so the
> include/library logic is really useless to us)
>
> The logic is around
> https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/Gnu.cpp#L1910
>
>Prefixes = --prefix/-B list (only the directory subset is effective)
>StringRef GCCToolchainDir = --gcc-toolchain= or CMake variable
> GCC_INSTALL_PREFIX
>if (GCCToolchainDir != "") {
> Prefixes.push_back(std::string(GCCToolchainDir));
>} else {
> if (!D.SysRoot.empty()) {
>Prefixes.push_back(D.SysRoot);
>// Add D.SysRoot+"/usr" to Prefixes. Some distributions add more
> directories.
>AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
> }
>
> // D.InstalledDir is the directory of the clang executable, e.g. /usr/bin
> Prefixes.push_back(D.InstalledDir + "/..");
>
> if (D.SysRoot.empty())
>AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
>}
>
>// Gentoo / ChromeOS specific logic.
>// I think this block is misplaced.
>if (GCCToolchainDir == "" || GCCToolchainDir == D.SysRoot + "/usr") {
> ...
>}
>
>// Loop over the various components which exist and select the best GCC
>// installation available. GCC installs are ranked by version number.
>Version = GCCVersion::Parse("0.0.0");
>for (const std::string : Prefixes) {
> auto = D.getVFS();
> if (!VFS.exists(Prefix))
>continue;
>
> // CandidateLibDirs is a subset of {/lib64, /lib32, /lib}.
> for (StringRef Suffix : CandidateLibDirs) {
>const std::string LibDir = Prefix + Suffix.str();
>if (!VFS.exists(LibDir))
> continue;
>bool GCCDirExists = VFS.exists(LibDir + "/gcc");
>bool GCCCrossDirExists = VFS.exists(LibDir + "/gcc-cross");
>
>// Precise match. Detect
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On 2021-03-03, Masahiro Yamada wrote:
Hi.
On Wed, Mar 3, 2021 at 6:44 AM Fangrui Song wrote:
Reviewed-by: Fangrui Song
Thanks for the clean-up!
--gcc-toolchain= is an obsscure way searching for GCC installation prefixes
(--prefix).
The logic is complex and different for different distributions/architectures.
If we specify --prefix= (-B) explicitly, --gcc-toolchain is not needed.
I tested this, and worked for me too.
Before applying this patch, could you please
help me understand the logic?
I checked the manual
(https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-b-dir)
-B, --prefix , --prefix=
Add to search path for binaries and object files used implicitly
--gcc-toolchain=, -gcc-toolchain
Use the gcc toolchain at the given directory
Hmm, this description is too concise
to understand how it works...
I use Ubuntu 20.10.
I use distro's default clang
located in /usr/bin/clang.
I place my aarch64 linaro toolchain in
/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu-gcc,
which is not in my PATH environment.
From my some experiments,
clang --target=aarch64-linux-gnu -no-integrated-as \
--prefix=/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu- ...
works almost equivalent to
PATH=/home/masahiro/tools/aarch64-linaro-7.5/bin:$PATH \
clang --target=aarch64-linux-gnu -no-integrated-as ...
Then, clang will pick up aarch64-linux-gnu-as
found in the search path.
Is this correct?
On the other hand, I could not understand
what the purpose of --gcc-toolchain= is.
Even if I add --gcc-toolchain=/home/masahiro/tools/aarch64-linaro-7.5,
it does not make any difference, and it is completely useless.
I read the comment from stephenhines:
https://github.com/ClangBuiltLinux/linux/issues/78
How could --gcc-toolchain be used
in a useful way?
--gcc-toolchain was introduced in
https://reviews.llvm.org/rG1af7c219c7113a35415651127f05cdf056b63110
to provide a flexible alternative to autoconf configure-time
--with-gcc-toolchain (now cmake variable GCC_INSTALL_PREFIX).
I agree the option is confusing, the documentation is poor, and probably very
few people understand what it does.
I apologize that my previous reply is not particular correct.
So the more correct answer is below:
A --prefix option can specify either of
1) A directory (for something like /a/b/lib/gcc/arm-linux-androideabi, this
should be /a/b, the parent directory of 'lib')
2) A path fragment like /usr/bin/aarch64-linux-gnu-
The directory values of the --prefix list and --gcc-toolchain are used to
detect GCC installation directories. The directory is used to fetch include
directories, system library directories and binutils directories (as, objcopy).
(See below, Linux kernel only needs the binutils executables, so the
include/library logic is really useless to us)
The logic is around
https://github.com/llvm/llvm-project/blob/main/clang/lib/Driver/ToolChains/Gnu.cpp#L1910
Prefixes = --prefix/-B list (only the directory subset is effective)
StringRef GCCToolchainDir = --gcc-toolchain= or CMake variable
GCC_INSTALL_PREFIX
if (GCCToolchainDir != "") {
Prefixes.push_back(std::string(GCCToolchainDir));
} else {
if (!D.SysRoot.empty()) {
Prefixes.push_back(D.SysRoot);
// Add D.SysRoot+"/usr" to Prefixes. Some distributions add more
directories.
AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
}
// D.InstalledDir is the directory of the clang executable, e.g. /usr/bin
Prefixes.push_back(D.InstalledDir + "/..");
if (D.SysRoot.empty())
AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
}
// Gentoo / ChromeOS specific logic.
// I think this block is misplaced.
if (GCCToolchainDir == "" || GCCToolchainDir == D.SysRoot + "/usr") {
...
}
// Loop over the various components which exist and select the best GCC
// installation available. GCC installs are ranked by version number.
Version = GCCVersion::Parse("0.0.0");
for (const std::string : Prefixes) {
auto = D.getVFS();
if (!VFS.exists(Prefix))
continue;
// CandidateLibDirs is a subset of {/lib64, /lib32, /lib}.
for (StringRef Suffix : CandidateLibDirs) {
const std::string LibDir = Prefix + Suffix.str();
if (!VFS.exists(LibDir))
continue;
bool GCCDirExists = VFS.exists(LibDir + "/gcc");
bool GCCCrossDirExists = VFS.exists(LibDir + "/gcc-cross");
// Precise match. Detect $Prefix/lib/$--target
ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, TargetTriple.str(),
false, GCCDirExists, GCCCrossDirExists);
// Usually empty.
for (StringRef Candidate : ExtraTripleAliases) // Try these first.
ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, Candidate, false,
GCCDirExists, GCCCrossDirExists);
// CandidateTripleAliases is a set with "x86_64-linux-gnu",
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On Wed, Mar 3, 2021 at 4:25 AM Sedat Dilek wrote: > > On Tue, Mar 2, 2021 at 10:07 PM Nathan Chancellor wrote: > > > > This is not necessary anymore now that we specify '--prefix=', which > > tells clang exactly where to find the GNU cross tools. This has been > > verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a > > distribution version of LLVM 11.1.0 without binutils in the LLVM > > toolchain locations. > > > > Signed-off-by: Nathan Chancellor > > [ CC Behan ] > > Hahaha, that is a change of a very early commit in times of the > LLVM/Clang Linux-kernel development. > So-to-say a historical change :-). > > I will try this patchset later with latest Linux -v5.12-rc1+ and my > custom patchset. > I tested these two patches in my build environment. So far no issues. NOTE: I have not tested the combo: Clang and GNU AS. Tested-by: Sedat Dilek # LLVM/Clang v13-git - Sedat - > > --- > > Makefile | 4 > > 1 file changed, 4 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index f9b54da2fca0..c20f0ad8be73 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) > > CLANG_FLAGS+= --target=$(notdir $(CROSS_COMPILE:%-=%)) > > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > > CLANG_FLAGS+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > > -GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > > -endif > > -ifneq ($(GCC_TOOLCHAIN),) > > -CLANG_FLAGS+= --gcc-toolchain=$(GCC_TOOLCHAIN) > > endif > > ifneq ($(LLVM_IAS),1) > > CLANG_FLAGS+= -no-integrated-as > > > > base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb > > -- > > 2.31.0.rc0.75.gec125d1bc1 > > > > -- > > You received this message because you are subscribed to the Google Groups > > "Clang Built Linux" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to clang-built-linux+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/clang-built-linux/20210302210646.3044738-1-nathan%40kernel.org.
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
Hi. On Wed, Mar 3, 2021 at 6:44 AM Fangrui Song wrote: > > Reviewed-by: Fangrui Song > > Thanks for the clean-up! > --gcc-toolchain= is an obsscure way searching for GCC installation prefixes > (--prefix). > The logic is complex and different for different distributions/architectures. > > If we specify --prefix= (-B) explicitly, --gcc-toolchain is not needed. I tested this, and worked for me too. Before applying this patch, could you please help me understand the logic? I checked the manual (https://clang.llvm.org/docs/ClangCommandLineReference.html#cmdoption-clang-b-dir) -B, --prefix , --prefix= Add to search path for binaries and object files used implicitly --gcc-toolchain=, -gcc-toolchain Use the gcc toolchain at the given directory Hmm, this description is too concise to understand how it works... I use Ubuntu 20.10. I use distro's default clang located in /usr/bin/clang. I place my aarch64 linaro toolchain in /home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu-gcc, which is not in my PATH environment. >From my some experiments, clang --target=aarch64-linux-gnu -no-integrated-as \ --prefix=/home/masahiro/tools/aarch64-linaro-7.5/bin/aarch64-linux-gnu- ... works almost equivalent to PATH=/home/masahiro/tools/aarch64-linaro-7.5/bin:$PATH \ clang --target=aarch64-linux-gnu -no-integrated-as ... Then, clang will pick up aarch64-linux-gnu-as found in the search path. Is this correct? On the other hand, I could not understand what the purpose of --gcc-toolchain= is. Even if I add --gcc-toolchain=/home/masahiro/tools/aarch64-linaro-7.5, it does not make any difference, and it is completely useless. I read the comment from stephenhines: https://github.com/ClangBuiltLinux/linux/issues/78 How could --gcc-toolchain be used in a useful way? > On 2021-03-02, Nathan Chancellor wrote: > >This is not necessary anymore now that we specify '--prefix=', which > >tells clang exactly where to find the GNU cross tools. This has been > >verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a > >distribution version of LLVM 11.1.0 without binutils in the LLVM > >toolchain locations. > > > >Signed-off-by: Nathan Chancellor > >--- > > Makefile | 4 > > 1 file changed, 4 deletions(-) > > > >diff --git a/Makefile b/Makefile > >index f9b54da2fca0..c20f0ad8be73 100644 > >--- a/Makefile > >+++ b/Makefile > >@@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) > > CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) > > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > > CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > >-GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > >-endif > >-ifneq ($(GCC_TOOLCHAIN),) > >-CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN) > > endif > > ifneq ($(LLVM_IAS),1) > > CLANG_FLAGS += -no-integrated-as > > > >base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb > >-- > >2.31.0.rc0.75.gec125d1bc1 > > > >-- > >You received this message because you are subscribed to the Google Groups > >"Clang Built Linux" group. > >To unsubscribe from this group and stop receiving emails from it, send an > >email to clang-built-linux+unsubscr...@googlegroups.com. > >To view this discussion on the web visit > >https://groups.google.com/d/msgid/clang-built-linux/20210302210646.3044738-1-nathan%40kernel.org. -- Best Regards Masahiro Yamada
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On Tue, Mar 2, 2021 at 10:07 PM Nathan Chancellor wrote: > > This is not necessary anymore now that we specify '--prefix=', which > tells clang exactly where to find the GNU cross tools. This has been > verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a > distribution version of LLVM 11.1.0 without binutils in the LLVM > toolchain locations. > > Signed-off-by: Nathan Chancellor [ CC Behan ] Hahaha, that is a change of a very early commit in times of the LLVM/Clang Linux-kernel development. So-to-say a historical change :-). I will try this patchset later with latest Linux -v5.12-rc1+ and my custom patchset. Thanks. - Sedat - > --- > Makefile | 4 > 1 file changed, 4 deletions(-) > > diff --git a/Makefile b/Makefile > index f9b54da2fca0..c20f0ad8be73 100644 > --- a/Makefile > +++ b/Makefile > @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) > CLANG_FLAGS+= --target=$(notdir $(CROSS_COMPILE:%-=%)) > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > CLANG_FLAGS+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > -GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > -endif > -ifneq ($(GCC_TOOLCHAIN),) > -CLANG_FLAGS+= --gcc-toolchain=$(GCC_TOOLCHAIN) > endif > ifneq ($(LLVM_IAS),1) > CLANG_FLAGS+= -no-integrated-as > > base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb > -- > 2.31.0.rc0.75.gec125d1bc1 > > -- > You received this message because you are subscribed to the Google Groups > "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clang-built-linux+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/clang-built-linux/20210302210646.3044738-1-nathan%40kernel.org.
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
On Tue, Mar 2, 2021 at 1:07 PM Nathan Chancellor wrote: > > This is not necessary anymore now that we specify '--prefix=', which > tells clang exactly where to find the GNU cross tools. This has been > verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a > distribution version of LLVM 11.1.0 without binutils in the LLVM > toolchain locations. > > Signed-off-by: Nathan Chancellor Thanks for the patch! Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers I see this pattern still being used in arch/arm64/kernel/vdso32/Makefile, but that can be separate cleanups. > --- > Makefile | 4 > 1 file changed, 4 deletions(-) > > diff --git a/Makefile b/Makefile > index f9b54da2fca0..c20f0ad8be73 100644 > --- a/Makefile > +++ b/Makefile > @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) > CLANG_FLAGS+= --target=$(notdir $(CROSS_COMPILE:%-=%)) > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > CLANG_FLAGS+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) > -GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > -endif > -ifneq ($(GCC_TOOLCHAIN),) > -CLANG_FLAGS+= --gcc-toolchain=$(GCC_TOOLCHAIN) > endif > ifneq ($(LLVM_IAS),1) > CLANG_FLAGS+= -no-integrated-as > > base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb > -- > 2.31.0.rc0.75.gec125d1bc1 > -- Thanks, ~Nick Desaulniers
Re: [PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
Reviewed-by: Fangrui Song Thanks for the clean-up! --gcc-toolchain= is an obsscure way searching for GCC installation prefixes (--prefix). The logic is complex and different for different distributions/architectures. If we specify --prefix= (-B) explicitly, --gcc-toolchain is not needed. On 2021-03-02, Nathan Chancellor wrote: This is not necessary anymore now that we specify '--prefix=', which tells clang exactly where to find the GNU cross tools. This has been verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a distribution version of LLVM 11.1.0 without binutils in the LLVM toolchain locations. Signed-off-by: Nathan Chancellor --- Makefile | 4 1 file changed, 4 deletions(-) diff --git a/Makefile b/Makefile index f9b54da2fca0..c20f0ad8be73 100644 --- a/Makefile +++ b/Makefile @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) -GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) -endif -ifneq ($(GCC_TOOLCHAIN),) -CLANG_FLAGS+= --gcc-toolchain=$(GCC_TOOLCHAIN) endif ifneq ($(LLVM_IAS),1) CLANG_FLAGS += -no-integrated-as base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb -- 2.31.0.rc0.75.gec125d1bc1 -- You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210302210646.3044738-1-nathan%40kernel.org.
[PATCH 1/2] Makefile: Remove '--gcc-toolchain' flag
This is not necessary anymore now that we specify '--prefix=', which tells clang exactly where to find the GNU cross tools. This has been verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as well as a distribution version of LLVM 11.1.0 without binutils in the LLVM toolchain locations. Signed-off-by: Nathan Chancellor --- Makefile | 4 1 file changed, 4 deletions(-) diff --git a/Makefile b/Makefile index f9b54da2fca0..c20f0ad8be73 100644 --- a/Makefile +++ b/Makefile @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),) CLANG_FLAGS+= --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS+= --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) -GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) -endif -ifneq ($(GCC_TOOLCHAIN),) -CLANG_FLAGS+= --gcc-toolchain=$(GCC_TOOLCHAIN) endif ifneq ($(LLVM_IAS),1) CLANG_FLAGS+= -no-integrated-as base-commit: 7a7fd0de4a9804299793e564a555a49c1fc924cb -- 2.31.0.rc0.75.gec125d1bc1
