6063a8fbcf
Currently, the internal toolchain backend does a three stage gcc
build, with the following sequence of builds:
- build gcc-initial
- configure libc, install headers and start files
- build gcc-intermediate
- build libc
- build gcc-final
However, it turns out that this is not necessary, and only a two stage
gcc build is needed. At some point, it was believed that a three stage
gcc build was needed for NPTL based toolchains with old gcc versions,
but even a gcc 4.4 build with a NPTL toolchain works fine.
So, this commit switches the internal toolchain backend to use a two
stage gcc build: just gcc-initial and gcc-final. It does so by:
* Removing the custom dependency of all C libraries build step to
host-gcc-intermediate. Now the C library packages simply have to
depend on host-gcc-initial as a normal dependency (which they
already do), and that's it.
* Build and install both gcc *and* libgcc in
host-gcc-initial. Previously, only gcc was built and installed in
host-gcc-initial. libgcc was only done in host-gcc-intermediate,
but now we need libgcc to build the C library.
* Pass appropriate environment variables to get SSP (Stack Smashing
Protection) to work properly:
- Tell the compiler that the libc will provide the SSP support, by
passing gcc_cv_libc_provides_ssp=yes. In Buildroot, we have
chosen to use the SSP support from the C library instead of the
SSP support from the compiler (this is not changed by this patch
series, it was already the case).
- Tell glibc to *not* build its own programs with SSP support. The
issue is that if glibc detects that the compiler supports
-fstack-protector, then glibc uses it to build a few things with
SSP. However, at this point, the support is not complete (we
only have host-gcc-initial, and the C library is not completely
built). So, we pass libc_cv_ssp=no to tell the C library to not
use SSP support itself. Note that this is not a big loss: only a
few parts of the C library were built with -fstack-protector,
not the entire library.
* A special change is needed for ARC, because its libgcc depends on
the C library, which breaks building libgcc in
host-gcc-initial. This looks like a bug in the ARC compiler, as it
does not obey the inhibit_libc variable which tells the compiler
build process to *not* enable things that depend on the C
library. So for now, in host-gcc-initial, we simply disable the
build of libgmon.a for ARC. It's going to be built as part of
host-gcc-final, so the final compiler will have gmon support.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
60 lines
2.0 KiB
Makefile
60 lines
2.0 KiB
Makefile
################################################################################
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#
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# gcc-initial
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#
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################################################################################
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GCC_INITIAL_VERSION = $(GCC_VERSION)
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GCC_INITIAL_SITE = $(GCC_SITE)
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GCC_INITIAL_SOURCE = $(GCC_SOURCE)
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HOST_GCC_INITIAL_DEPENDENCIES = $(HOST_GCC_COMMON_DEPENDENCIES)
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HOST_GCC_INITIAL_EXTRACT_CMDS = $(HOST_GCC_EXTRACT_CMDS)
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ifneq ($(call qstrip, $(BR2_XTENSA_CORE_NAME)),)
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HOST_GCC_INITIAL_POST_EXTRACT_HOOKS += HOST_GCC_XTENSA_OVERLAY_EXTRACT
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endif
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HOST_GCC_INITIAL_POST_PATCH_HOOKS += HOST_GCC_APPLY_PATCHES
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# gcc doesn't support in-tree build, so we create a 'build'
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# subdirectory in the gcc sources, and build from there.
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HOST_GCC_INITIAL_SUBDIR = build
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HOST_GCC_INITIAL_PRE_CONFIGURE_HOOKS += HOST_GCC_CONFIGURE_SYMLINK
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# gcc on ARC has a bug: in its libgcc, even when no C library is
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# available (--with-newlib is passed, and therefore inhibit_libc is
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# defined), it tries to use the C library for the libgmon
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# library. Since it's not needed in gcc-initial, we disabled it here.
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ifeq ($(BR2_GCC_VERSION_4_8_ARC),y)
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define HOST_GCC_INITIAL_DISABLE_LIBGMON
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$(SED) 's/crtbeginS.o libgmon.a crtg.o/crtbeginS.o crtg.o/' \
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$(@D)/libgcc/config.host
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endef
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HOST_GCC_INITIAL_POST_PATCH_HOOKS += HOST_GCC_INITIAL_DISABLE_LIBGMON
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endif
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HOST_GCC_INITIAL_CONF_OPT = \
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$(HOST_GCC_COMMON_CONF_OPT) \
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--enable-languages=c \
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--disable-shared \
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--without-headers \
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--disable-threads \
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--with-newlib \
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--disable-largefile \
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--disable-nls \
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$(call qstrip,$(BR2_EXTRA_GCC_CONFIG_OPTIONS))
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HOST_GCC_INITIAL_CONF_ENV = \
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$(HOST_GCC_COMMON_CONF_ENV)
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# We need to tell gcc that the C library will be providing the ssp
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# support, as it can't guess it since the C library hasn't been built
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# yet (we're gcc-initial).
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HOST_GCC_INITIAL_MAKE_OPT = $(if $(BR2_TOOLCHAIN_HAS_SSP),gcc_cv_libc_provides_ssp=yes) all-gcc all-target-libgcc
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HOST_GCC_INITIAL_INSTALL_OPT = install-gcc install-target-libgcc
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$(eval $(host-autotools-package))
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