Hi, On Sat, 2026-01-17 at 22:23 +0100, John Paul Adrian Glaubitz wrote: > Hi, > > On Fri, 2026-01-16 at 16:47 +0000, Jessica Clarke wrote: > > On Fri, Jan 16, 2026 at 04:30:50PM +0100, Ludwig Rydberg wrote: > > > Add support for the clone3 system call to the SPARC architectures. > > > > > > The implementation follows the pattern of the original clone syscall. > > > However, instead of explicitly calling kernel_clone, the clone3 > > > handler calls the generic sys_clone3 handler in kernel/fork. > > > In case no stack is provided, the parents stack is reused. > > > > > > The return call conventions for clone on SPARC are kept for clone3: > > > Parent --> %o0 == child's pid, %o1 == 0 > > > Child --> %o0 == parent's pid, %o1 == 1 > > > > One of the benefits of having a new clone3 is that the interface can be > > made the same across all architectures*, unlike clone, which both passes > > the arguments in different orders for different architectures and, in > > the case of SPARC, has this weird return convention inherited from the > > SunOS syscall interface. Is there a good reason to deviate for clone3 > > too and keep this annoying oddity going, that requires special-casing > > SPARC when other architectures can just syscall(__NR_clone3, ...)? > > Very good point. Since clone3() is a new syscall, I think it would make more > sense to use the same interface as all the other architectures. > > The weird syscall interface was already the reason why we had to write custom > code for systemd on SPARC in order to use the raw clone() syscall. > > I think the proposed implementation of clone3() for SPARC would actually break > the libcamera build which calls clone3() using the syscall handler [1]: > > FAILED: [code=1] src/libcamera/libcamera.so.0.6.0.p/process.cpp.o > c++ -Isrc/libcamera/libcamera.so.0.6.0.p -Isrc/libcamera -I../src/libcamera > -Iinclude -I../include -Iinclude/libcamera -Iinclude/libcamera/ipa > -Iinclude/libcamera/internal -Isrc/libcamera/proxy - > I/usr/include/p11-kit-1 -I/usr/include/sparc64-linux-gnu > -fdiagnostics-color=always -D_GLIBCXX_ASSERTIONS=1 -D_FILE_OFFSET_BITS=64 > -Wall -Winvalid-pch -Wextra -Werror -std=c++17 -Wnon-virtual-dtor - > Wno-redundant-move -Wmissing-declarations -Wshadow -include > /build/reproducible-path/libcamera-0.6.0/obj-sparc64-linux-gnu/config.h -g > -O2 -ffile-prefix-map=/build/reproducible-path/libcamera-0.6.0=. > -fstack-protector-strong -Wformat -Werror=format-security -Wno-error > -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -DLIBCAMERA_BASE_PRIVATE -MD -MQ > src/libcamera/libcamera.so.0.6.0.p/process.cpp.o -MF > src/libcamera/libcamera.so.0.6.0.p/process.cpp.o.d -o > src/libcamera/libcamera.so.0.6.0.p/process.cpp.o -c > ../src/libcamera/process.cpp > ../src/libcamera/process.cpp: In member function ‘int > libcamera::Process::start(const std::string&, libcamera::Span<const > std::__cxx11::basic_string<char> >, libcamera::Span<const int>)’: > ../src/libcamera/process.cpp:160:33: error: ‘SYS_clone3’ was not declared in > this scope; did you mean ‘SYS_clone’? > 160 | long childPid = syscall(SYS_clone3, &cargs, sizeof(cargs)); > | ^~~~~~~~~~ > | SYS_clone > > I'll verify that and report back.
I can confirm that libcamera builds fine and passes its testsuite with a patched kernel: Ok: 38 Expected Fail: 1 Fail: 0 Skipped: 31 Full log written to /home/glaubitz/libcamera/libcamera-0.6.0/obj-sparc64-linux-gnu/meson-logs/testlog.txt make[1]: Leaving directory '/home/glaubitz/libcamera/libcamera-0.6.0' Whether the currently chosen interface is the right one, is another question though. Adrian -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
