[Buildroot] [PATCH/next/RFC v2 1/2] package/mariadb: handle missing ucontext_t

[Buildroot] [PATCH/next/RFC v2 1/2] package/mariadb: handle missing ucontext_t

[Bernd Kuhls]

On some archs uclibc does not provide ucontext_t, for details see
https://git.buildroot.net/buildroot/commit/?id=f1cbfeea95e6287c7a666aafc182ffa318eff262

Mariadb uses ucontext_t optionally, its use can be disabled by the
corresponding cmake option. Instead of copying the Config.in code from
libsigsegv we shamelessly use its ARCH_SUPPORTS option while thinking
that a more general approach might be needed for ucontext_t support so
please consider this patch a RFC.

This patch fixes a build error

In file included from /home/bernd/buildroot/output/build/mariadb-10.2.17/libmariadb/plugins/pvio/pvio_socket.c:32:0:
/home/bernd/buildroot/output/build/mariadb-10.2.17/libmariadb/include/ma_context.h:62:3: error: unknown type name ?ucontext_t?
   ucontext_t base_context;
   ^~~~~~~~~~

using this defconfig:

BR2_arcle=y
BR2_archs38=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.org/toolchains/tarballs/br-arcle-hs38-full-2018.02-926-gb393c24.tar.bz2"
BR2_TOOLCHAIN_EXTERNAL_GCC_7=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_1=y
BR2_TOOLCHAIN_EXTERNAL_LOCALE=y
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_PACKAGE_MYSQL=y
BR2_PACKAGE_MARIADB=y
BR2_PACKAGE_MARIADB_SERVER=y

Musl also does not provide ucontext functions:
https://wiki.musl-libc.org/open-issues.html

To fix this build error

[  6%] Linking C shared library libmariadb.so
CMakeFiles/mariadb_obj.dir/ma_context.c.o: In function `my_context_spawn_internal':
/home/bernd/buildroot/output/build/mariadb-10.3.9/libmariadb/libmariadb/ma_context.c:63: undefined reference to `setcontext'
CMakeFiles/mariadb_obj.dir/ma_context.c.o: In function `my_context_continue':
/home/bernd/buildroot/output/build/mariadb-10.3.9/libmariadb/libmariadb/ma_context.c:76: undefined reference to `swapcontext'
CMakeFiles/mariadb_obj.dir/ma_context.c.o: In function `my_context_spawn':
/home/bernd/buildroot/output/build/mariadb-10.3.9/libmariadb/libmariadb/ma_context.c:94: undefined reference to `getcontext'
/home/bernd/buildroot/output/build/mariadb-10.3.9/libmariadb/libmariadb/ma_context.c:104: undefined reference to `makecontext'
CMakeFiles/mariadb_obj.dir/ma_context.c.o: In function `my_context_yield':
/home/bernd/buildroot/output/build/mariadb-10.3.9/libmariadb/libmariadb/ma_context.c:119: undefined reference to `swapcontext'

we use the same cmake option instead of patching the source code like
void linux does:
https://github.com/void-linux/void-packages/blob/master/srcpkgs/mariadb/patches/musl_ucontext-h.patch

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
v2: added musl fix

 package/mariadb/mariadb.mk | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/package/mariadb/mariadb.mk b/package/mariadb/mariadb.mk
index 075582288a..e061cc53a8 100644
--- a/package/mariadb/mariadb.mk
+++ b/package/mariadb/mariadb.mk
@@ -61,6 +61,15 @@ else
 MARIADB_CONF_OPTS += -DWITHOUT_SERVER=ON
 endif
 
+# hack: do we need an ucontext-specific option?
+ifeq ($(BR2_PACKAGE_LIBSIGSEGV_ARCH_SUPPORTS),)
+MARIADB_CONF_OPTS += -DHAVE_UCONTEXT_H=0
+else
+ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y)
+MARIADB_CONF_OPTS += -DHAVE_UCONTEXT_H=0
+endif
+endif
+
 MARIADB_CONF_OPTS += \
 	-DINSTALL_DOCDIR=share/doc/mariadb-$(MARIADB_VERSION) \
 	-DINSTALL_DOCREADMEDIR=share/doc/mariadb-$(MARIADB_VERSION) \
-- 
2.18.0

[Buildroot] [PATCH/next v2 2/2] package/mariadb: bump version to 10.3.9

[Bernd Kuhls]

From: Peter Seiderer <ps.report@gmx.net>

Release notes: https://mariadb.com/kb/en/mariadb-1039-release-notes/
Changelog: https://mariadb.com/kb/en/mariadb-1039-changelog/

This bump also fixes broken atomic support for
BR2_TOOLCHAIN_HAS_LIBATOMIC=y with mariadb-10.2:

[ 59%] Linking CXX executable mariabackup
../../storage/innobase/libinnobase.a(handler0alter.cc.o): In function `my_atomic_add64':
/home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:274: undefined reference to `__sync_fetch_and_add_8'

with this defconfig

BR2_arcle=y
BR2_archs38=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.org/toolchains/tarballs/br-arcle-hs38-full-2018.02-926-gb393c24.tar.bz2"
BR2_TOOLCHAIN_EXTERNAL_GCC_7=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_1=y
BR2_TOOLCHAIN_EXTERNAL_LOCALE=y
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_PACKAGE_MYSQL=y
BR2_PACKAGE_MARIADB=y
BR2_PACKAGE_MARIADB_SERVER=y

Adding "-latomic" to CXXFLAGS and/or adding -DHAVE_GCC_ATOMIC_BUILTINS=1
to CONF_OPTS, like we do for mariadb-10.3, does not fix the build error
with mariadb-10.2. There the build would stop even earlier without these
options:

/home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:138:2:
 error: #error atomic ops for this platform are not implemented
 #error atomic ops for this platform are not implemented

Mariadb-10.3 contains improved atomic support, this build error does
not occur here.

Updated license hash of README.md after upstream commits:
https://github.com/MariaDB/server/commits/10.3/README.md

my-small.cnf.sh is not provided anymore by upstream:
https://github.com/MariaDB/server/commit/7fee164faf8fce7be4ebe322d2178efd3d075eae

[Peter Seiderer: bumped to version 10.3.7]
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
[Bernd: bumped to version 10.3.9, fixed atomic support,
 fixed my-small.cnf.sh, updated license hash]
Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
v2: - removed WITH_SSL change (Thomas)
    - added atomic dependencies to Config.in (Thomas)

 package/mariadb/mariadb.hash | 12 ++++++------
 package/mariadb/mariadb.mk   | 11 ++++++++---
 package/mysql/Config.in      |  2 ++
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/package/mariadb/mariadb.hash b/package/mariadb/mariadb.hash
index d44b4f35ab..41e60037be 100644
--- a/package/mariadb/mariadb.hash
+++ b/package/mariadb/mariadb.hash
@@ -1,9 +1,9 @@
-# From https://downloads.mariadb.org/mariadb/10.2.17/
-md5 97dac7c5c288dbbbdd97768972daeb2e  mariadb-10.2.17.tar.gz
-sha1 38f2ba16297e14baa2f641d2273bbb92f56d0b94  mariadb-10.2.17.tar.gz
-sha256 e7b3078f8de874a4d451242a8a3eed49bf6f916dcd52fc3efa55886f5f35be27  mariadb-10.2.17.tar.gz
-sha512 9714f786abde43b418d8b5accbbd485de213b90db18c879625ce30777526d28fdafd3bdb43922ab6872b300cfa06895b5b3fad5eb0c0e804ad66a1fd1793a141  mariadb-10.2.17.tar.gz
+# From https://downloads.mariadb.org/mariadb/10.3.9
+md5 39c871e65134aabbc12c856691912435  mariadb-10.3.9.tar.gz
+sha1 51e9870847daa76f1e82ade97d9cf60a31df7656  mariadb-10.3.9.tar.gz
+sha256 561c6969bbd24dbb22d1d196a6b037665389b91e6dab881f39c5616389f156f4  mariadb-10.3.9.tar.gz
+sha512 7c7a678fb0c85da64b6df3df17b8cf7f2ccf862e27dcf8535f7403f8693c76b3b1a912f4b6ca876a591ada60a99577a947bfe7a63c602f754332e1e4f689e6e7  mariadb-10.3.9.tar.gz
 
 # Hash for license files
-sha256 dec3c92fdc58070facec08db681aa6b9cb05fd21e463358161c1df92e1c0653f  README.md
+sha256 5baa5057c525cacc9f7814215582ac150e5bb0b0007aa8f6ebc50a5c1b7a496d  README.md
 sha256 ab15fd526bd8dd18a9e77ebc139656bf4d33e97fc7238cd11bf60e2b9b8666c6  COPYING
diff --git a/package/mariadb/mariadb.mk b/package/mariadb/mariadb.mk
index e061cc53a8..bc22ff6c59 100644
--- a/package/mariadb/mariadb.mk
+++ b/package/mariadb/mariadb.mk
@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-MARIADB_VERSION = 10.2.17
+MARIADB_VERSION = 10.3.9
 MARIADB_SITE = https://downloads.mariadb.org/interstitial/mariadb-$(MARIADB_VERSION)/source
 MARIADB_LICENSE = GPL-2.0 (server), GPL-2.0 with FLOSS exception (GPL client library), LGPL-2.0 (LGPL client library)
 # Tarball no longer contains LGPL license text
@@ -70,7 +70,14 @@ MARIADB_CONF_OPTS += -DHAVE_UCONTEXT_H=0
 endif
 endif
 
+MARIADB_CXXFLAGS = $(TARGET_CXXFLAGS)
+
+ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
+MARIADB_CXXFLAGS += -latomic
+endif
+
 MARIADB_CONF_OPTS += \
+	-DCMAKE_CXX_FLAGS="$(MARIADB_CXXFLAGS)" \
 	-DINSTALL_DOCDIR=share/doc/mariadb-$(MARIADB_VERSION) \
 	-DINSTALL_DOCREADMEDIR=share/doc/mariadb-$(MARIADB_VERSION) \
 	-DINSTALL_MANDIR=share/man \
@@ -125,8 +132,6 @@ endif
 # We also don't need the test suite on the target
 define MARIADB_POST_INSTALL
 	mkdir -p $(TARGET_DIR)/var/lib/mysql
-	$(INSTALL) -D -m 644 $(TARGET_DIR)/usr/share/mysql/my-small.cnf \
-		$(TARGET_DIR)/etc/mysql/my.cnf
 	$(RM) $(TARGET_DIR)/usr/bin/mysql_config
 	$(RM) -r $(TARGET_DIR)/usr/share/mysql/test
 endef
diff --git a/package/mysql/Config.in b/package/mysql/Config.in
index ccc014e272..6409c8b806 100644
--- a/package/mysql/Config.in
+++ b/package/mysql/Config.in
@@ -17,6 +17,7 @@ choice
 config BR2_PACKAGE_MARIADB
 	bool "mariadb"
 	depends on !BR2_STATIC_LIBS
+	depends on BR2_TOOLCHAIN_HAS_ATOMIC || BR2_TOOLCHAIN_HAS_SYNC_8
 	select BR2_PACKAGE_LIBAIO
 	select BR2_PACKAGE_LIBXML2
 	select BR2_PACKAGE_NCURSES
@@ -32,6 +33,7 @@ config BR2_PACKAGE_MARIADB
 
 comment "mariadb needs a toolchain w/ dynamic library"
 	depends on BR2_STATIC_LIBS
+	depends on BR2_TOOLCHAIN_HAS_ATOMIC || BR2_TOOLCHAIN_HAS_SYNC_8
 
 config BR2_PACKAGE_ORACLE_MYSQL
 	bool "oracle mysql"
-- 
2.18.0

[Buildroot] [PATCH/next v2 2/2] package/mariadb: bump version to 10.3.9

[Ryan Coe]

Bernd, Peter, All,

On 8/26/2018 10:03 AM, Bernd Kuhls wrote:
> From: Peter Seiderer <ps.report@gmx.net>
>
> Release notes: https://mariadb.com/kb/en/mariadb-1039-release-notes/
> Changelog: https://mariadb.com/kb/en/mariadb-1039-changelog/
>
> This bump also fixes broken atomic support for
> BR2_TOOLCHAIN_HAS_LIBATOMIC=y with mariadb-10.2:
>
> [ 59%] Linking CXX executable mariabackup
> ../../storage/innobase/libinnobase.a(handler0alter.cc.o): In function `my_atomic_add64':
> /home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:274: undefined reference to `__sync_fetch_and_add_8'
>
> with this defconfig
>
> BR2_arcle=y
> BR2_archs38=y
> BR2_TOOLCHAIN_EXTERNAL=y
> BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
> BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
> BR2_TOOLCHAIN_EXTERNAL_URL="http://autobuild.buildroot.org/toolchains/tarballs/br-arcle-hs38-full-2018.02-926-gb393c24.tar.bz2"
> BR2_TOOLCHAIN_EXTERNAL_GCC_7=y
> BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_1=y
> BR2_TOOLCHAIN_EXTERNAL_LOCALE=y
> BR2_TOOLCHAIN_EXTERNAL_CXX=y
> BR2_PACKAGE_MYSQL=y
> BR2_PACKAGE_MARIADB=y
> BR2_PACKAGE_MARIADB_SERVER=y
>
> Adding "-latomic" to CXXFLAGS and/or adding -DHAVE_GCC_ATOMIC_BUILTINS=1
> to CONF_OPTS, like we do for mariadb-10.3, does not fix the build error
> with mariadb-10.2. There the build would stop even earlier without these
> options:
>
> /home/bernd/buildroot/output/build/mariadb-10.2.17/include/my_atomic.h:138:2:
>   error: #error atomic ops for this platform are not implemented
>   #error atomic ops for this platform are not implemented
>
> Mariadb-10.3 contains improved atomic support, this build error does
> not occur here.
>
> Updated license hash of README.md after upstream commits:
> https://github.com/MariaDB/server/commits/10.3/README.md
>
> my-small.cnf.sh is not provided anymore by upstream:
> https://github.com/MariaDB/server/commit/7fee164faf8fce7be4ebe322d2178efd3d075eae
>
> [Peter Seiderer: bumped to version 10.3.7]
> Signed-off-by: Peter Seiderer <ps.report@gmx.net>
> [Bernd: bumped to version 10.3.9, fixed atomic support,
>   fixed my-small.cnf.sh, updated license hash]
> Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Tested-by: Ryan Coe <bluemrp9@gmail.com>
> ---
> v2: - removed WITH_SSL change (Thomas)
>      - added atomic dependencies to Config.in (Thomas)
>
>   package/mariadb/mariadb.hash | 12 ++++++------
>   package/mariadb/mariadb.mk   | 11 ++++++++---
>   package/mysql/Config.in      |  2 ++
>   3 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/package/mariadb/mariadb.hash b/package/mariadb/mariadb.hash
> index d44b4f35ab..41e60037be 100644
> --- a/package/mariadb/mariadb.hash
> +++ b/package/mariadb/mariadb.hash
> @@ -1,9 +1,9 @@
> -# From https://downloads.mariadb.org/mariadb/10.2.17/
> -md5 97dac7c5c288dbbbdd97768972daeb2e  mariadb-10.2.17.tar.gz
> -sha1 38f2ba16297e14baa2f641d2273bbb92f56d0b94  mariadb-10.2.17.tar.gz
> -sha256 e7b3078f8de874a4d451242a8a3eed49bf6f916dcd52fc3efa55886f5f35be27  mariadb-10.2.17.tar.gz
> -sha512 9714f786abde43b418d8b5accbbd485de213b90db18c879625ce30777526d28fdafd3bdb43922ab6872b300cfa06895b5b3fad5eb0c0e804ad66a1fd1793a141  mariadb-10.2.17.tar.gz
> +# From https://downloads.mariadb.org/mariadb/10.3.9
> +md5 39c871e65134aabbc12c856691912435  mariadb-10.3.9.tar.gz
> +sha1 51e9870847daa76f1e82ade97d9cf60a31df7656  mariadb-10.3.9.tar.gz
> +sha256 561c6969bbd24dbb22d1d196a6b037665389b91e6dab881f39c5616389f156f4  mariadb-10.3.9.tar.gz
> +sha512 7c7a678fb0c85da64b6df3df17b8cf7f2ccf862e27dcf8535f7403f8693c76b3b1a912f4b6ca876a591ada60a99577a947bfe7a63c602f754332e1e4f689e6e7  mariadb-10.3.9.tar.gz
>   
>   # Hash for license files
> -sha256 dec3c92fdc58070facec08db681aa6b9cb05fd21e463358161c1df92e1c0653f  README.md
> +sha256 5baa5057c525cacc9f7814215582ac150e5bb0b0007aa8f6ebc50a5c1b7a496d  README.md
>   sha256 ab15fd526bd8dd18a9e77ebc139656bf4d33e97fc7238cd11bf60e2b9b8666c6  COPYING
> diff --git a/package/mariadb/mariadb.mk b/package/mariadb/mariadb.mk
> index e061cc53a8..bc22ff6c59 100644
> --- a/package/mariadb/mariadb.mk
> +++ b/package/mariadb/mariadb.mk
> @@ -4,7 +4,7 @@
>   #
>   ################################################################################
>   
> -MARIADB_VERSION = 10.2.17
> +MARIADB_VERSION = 10.3.9
>   MARIADB_SITE = https://downloads.mariadb.org/interstitial/mariadb-$(MARIADB_VERSION)/source
>   MARIADB_LICENSE = GPL-2.0 (server), GPL-2.0 with FLOSS exception (GPL client library), LGPL-2.0 (LGPL client library)
>   # Tarball no longer contains LGPL license text
> @@ -70,7 +70,14 @@ MARIADB_CONF_OPTS += -DHAVE_UCONTEXT_H=0
>   endif
>   endif
>   
> +MARIADB_CXXFLAGS = $(TARGET_CXXFLAGS)
> +
> +ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
> +MARIADB_CXXFLAGS += -latomic
> +endif
> +
>   MARIADB_CONF_OPTS += \
> +	-DCMAKE_CXX_FLAGS="$(MARIADB_CXXFLAGS)" \
>   	-DINSTALL_DOCDIR=share/doc/mariadb-$(MARIADB_VERSION) \
>   	-DINSTALL_DOCREADMEDIR=share/doc/mariadb-$(MARIADB_VERSION) \
>   	-DINSTALL_MANDIR=share/man \
> @@ -125,8 +132,6 @@ endif
>   # We also don't need the test suite on the target
>   define MARIADB_POST_INSTALL
>   	mkdir -p $(TARGET_DIR)/var/lib/mysql
> -	$(INSTALL) -D -m 644 $(TARGET_DIR)/usr/share/mysql/my-small.cnf \
> -		$(TARGET_DIR)/etc/mysql/my.cnf
>   	$(RM) $(TARGET_DIR)/usr/bin/mysql_config
>   	$(RM) -r $(TARGET_DIR)/usr/share/mysql/test
>   endef
> diff --git a/package/mysql/Config.in b/package/mysql/Config.in
> index ccc014e272..6409c8b806 100644
> --- a/package/mysql/Config.in
> +++ b/package/mysql/Config.in
> @@ -17,6 +17,7 @@ choice
>   config BR2_PACKAGE_MARIADB
>   	bool "mariadb"
>   	depends on !BR2_STATIC_LIBS
> +	depends on BR2_TOOLCHAIN_HAS_ATOMIC || BR2_TOOLCHAIN_HAS_SYNC_8
>   	select BR2_PACKAGE_LIBAIO
>   	select BR2_PACKAGE_LIBXML2
>   	select BR2_PACKAGE_NCURSES
> @@ -32,6 +33,7 @@ config BR2_PACKAGE_MARIADB
>   
>   comment "mariadb needs a toolchain w/ dynamic library"
>   	depends on BR2_STATIC_LIBS
> +	depends on BR2_TOOLCHAIN_HAS_ATOMIC || BR2_TOOLCHAIN_HAS_SYNC_8
>   
>   config BR2_PACKAGE_ORACLE_MYSQL
>   	bool "oracle mysql"

[Buildroot] [PATCH/next/RFC v2 1/2] package/mariadb: handle missing ucontext_t

[Thomas Petazzoni]

Hello Bernd,

+Waldemar in Cc, since there is (in my opinion) something not really
good going on in uClibc-ng, see below.

On Sun, 26 Aug 2018 19:03:25 +0200, Bernd Kuhls wrote:
> On some archs uclibc does not provide ucontext_t, for details see
> https://git.buildroot.net/buildroot/commit/?id=f1cbfeea95e6287c7a666aafc182ffa318eff262
> 
> Mariadb uses ucontext_t optionally, its use can be disabled by the
> corresponding cmake option. Instead of copying the Config.in code from
> libsigsegv we shamelessly use its ARCH_SUPPORTS option while thinking
> that a more general approach might be needed for ucontext_t support so
> please consider this patch a RFC.

Indeed, hijacking the libsigsegv Config.in symbol is not really nice.
Having a global BR2_TOOLCHAIN_HAS_UCONTEXT symbol would be OK, but I
believe in the case of mariadb, it shouldn't be needed.

Indeed, MariaDB configure.cmake contains this:

CHECK_INCLUDE_FILE(ucontext.h HAVE_UCONTEXT_H)
IF(NOT HAVE_UCONTEXT_H)
  CHECK_INCLUDE_FILE(sys/ucontext.h HAVE_UCONTEXT_H)
ENDIF()
IF(HAVE_UCONTEXT_H)
  CHECK_FUNCTION_EXISTS(makecontext HAVE_UCONTEXT_H)
ENDIF()

Which should do the following:

 - Check if ucontext.h exists, and if so, define HAVE_UCONTEXT_H

 - If HAVE_UCONTEXT_H is still not defined, check if sys/ucontext.h
   exists, and if it's the case, define HAVE_UCONTEXT_H

 - If HAVE_UCONTEXT_H is defined, test if makecontext exists, and store
   the result in HAVE_UCONTEXT_H.

So in our case, because makecontext() is not implemented, mariadb
should not use ucontext support.

But this doesn't work, because that's not how CHECK_FUNCTION_EXISTS()
work. If the variable passed is already defined to one, then it does
nothing.

So, can you change to something like this:

CHECK_INCLUDE_FILE(ucontext.h HAVE_UCONTEXT_H)
IF(NOT HAVE_UCONTEXT_H)
  CHECK_INCLUDE_FILE(sys/ucontext.h HAVE_UCONTEXT_H)
ENDIF()
CHECK_FUNCTION_EXISTS(makecontext HAVE_MAKECONTEXT)
IF(NOT HAVE_MAKECONTEXT)
  UNSET(HAVE_UCONTEXT_H)
ENDIF()

it should work a bit better. Beware that there are two locations where
ucontext.h is tested:

 - in configure.cmake
 - in libmariadb/cmake/CheckIncludeFiles.cmake

Side note for Waldemar: uClibc-ng approach here is a bit unclean: it
installs <ucontext.h> even if the architecture doesn't support the
context functions. And this <ucontext.h> does basically nothing,
because its entire contents are enclosed in an
__UCLIBC_HAS_CONTEXT_FUNCS__ condition. Waldemar: perhaps this should
be fixed in uClibc-ng ?

> Musl also does not provide ucontext functions:
> https://wiki.musl-libc.org/open-issues.html

This is interesting, because it shows that the comment in
libsigsegv/Config.in is not correct:

        # with glibc/musl, ucontext is available for all supported
        # architectures
        default y if BR2_TOOLCHAIN_USES_GLIBC
        default y if BR2_TOOLCHAIN_USES_MUSL

What is available for all architectures is ucontext.h, but the context
functions are not available for any architecture. So, libsigsegv needs
ucontext.h, not the context functions.

Could you have a look at fixing the CMake logic in MariaDB to rely on
the presence of makecontext() to decide automatically if ucontext
should be used or not ?

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com