794c325947 ("arch/x64:Syscall support is enabled by default", 2025-05-27)
changed nine guards from CONFIG_LIB_SYSCALL to CONFIG_ARCH_HAVE_SYSCALL but
never added the Kconfig symbol. Only ARCH_HAVE_SYSCALL_HOOKS exists in tree;
ARCH_HAVE_SYSCALL itself is defined nowhere, so it is always unset and since
that commit x86_64 has had no x86_64_syscall_entry(), no x86_64_syscall(), no
IA32_LSTAR/IA32_STAR programming and no syscall stub layer in any
configuration:
arch/x86_64/src/common/Make.defs:37 x86_64_syscall.c not compiled
arch/x86_64/src/common/CMakeLists.txt:41 likewise
arch/x86_64/include/irq.h:86
arch/x86_64/src/intel64/intel64_cpu.c:247, :386
arch/x86_64/src/intel64/intel64_head.S:83, :351, :538
arch/x86_64/src/intel64/intel64_saveusercontext.S:108
qemu-intel64:knsh_romfs and qemu-intel64:knsh_romfs_pci are the two
CONFIG_BUILD_KERNEL configurations in tree, and neither can have worked in
that time. They still link -- nothing references the missing pieces, so
libstubs.a is simply never pulled in -- and then die the first time user code
executes SYSCALL.
Define the symbol with the condition the code had before that commit, which
is LIB_SYSCALL: every protected and every kernel build needs the interface,
and a flat build is left exactly as it is today.
Impact: restores the system call interface for CONFIG_BUILD_KERNEL and
CONFIG_BUILD_PROTECTED on x86_64. CONFIG_BUILD_FLAT is unaffected --
qemu-intel64:nsh still builds with ARCH_HAVE_SYSCALL unset.
Assisted-by: Claude:claude-opus-5
Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>
5f9edeb6e6