kernel/linux.git/Documentation/features, branch master

Merge tag 'riscv-for-linus-7.1-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2026-04-24T17:00:37+00:00

Pull RISC-V updates from Paul Walmsley: "There is one significant change outside arch/riscv in this pull request: the addition of a set of KUnit tests for strlen(), strnlen(), and strrchr(). Otherwise, the most notable changes are to add some RISC-V-specific string function implementations, to remove XIP kernel support, to add hardware error exception handling, and to optimize our runtime unaligned access speed testing. A few comments on the motivation for removing XIP support. It's been broken in the RISC-V kernel for months. The code is not easy to maintain. Furthermore, for XIP support to truly be useful for RISC-V, we think that compile-time feature switches would need to be added for many of the RISC-V ISA features and microarchitectural properties that are currently implemented with runtime patching. No one has stepped forward to take responsibility for that work, so many of us think it's best to remove it until clear use cases and champions emerge. Summary: - Add Kunit correctness testing and microbenchmarks for strlen(), strnlen(), and strrchr() - Add RISC-V-specific strnlen(), strchr(), strrchr() implementations - Add hardware error exception handling - Clean up and optimize our unaligned access probe code - Enable HAVE_IOREMAP_PROT to be able to use generic_access_phys() - Remove XIP kernel support - Warn when addresses outside the vmemmap range are passed to vmemmap_populate() - Update the ACPI FADT revision check to warn if it's not at least ACPI v6.6, which is when key RISC-V-specific tables were added to the specification - Increase COMMAND_LINE_SIZE to 2048 to match ARM64, x86, PowerPC, etc. - Make kaslr_offset() a static inline function, since there's no need for it to show up in the symbol table - Add KASLR offset and SATP to the VMCOREINFO ELF notes to improve kdump support - Add Makefile cleanup rule for vdso_cfi copied source files, and add a .gitignore for the build artifacts in that directory - Remove some redundant ifdefs that check Kconfig macros - Add missing SPDX license tag to the CFI selftest - Simplify UTS_MACHINE assignment in the RISC-V Makefile - Clarify some unclear comments and remove some superfluous comments - Fix various English typos across the RISC-V codebase" * tag 'riscv-for-linus-7.1-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (31 commits) riscv: Remove support for XIP kernel riscv: Reuse compare_unaligned_access() in check_vector_unaligned_access() riscv: Split out compare_unaligned_access() riscv: Reuse measure_cycles() in check_vector_unaligned_access() riscv: Split out measure_cycles() for reuse riscv: Clean up & optimize unaligned scalar access probe riscv: lib: add strrchr() implementation riscv: lib: add strchr() implementation riscv: lib: add strnlen() implementation lib/string_kunit: extend benchmarks to strnlen() and chr searches lib/string_kunit: add performance benchmark for strlen() lib/string_kunit: add correctness test for strrchr() lib/string_kunit: add correctness test for strnlen() lib/string_kunit: add correctness test for strlen() riscv: vdso_cfi: Add .gitignore for build artifacts riscv: vdso_cfi: Add clean rule for copied sources riscv: enable HAVE_IOREMAP_PROT riscv: mm: WARN_ON() for bad addresses in vmemmap_populate() riscv: acpi: update FADT revision check to 6.6 riscv: add hardware error trap handler support ...

Merge tag 'alpha-for-v7.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/lindholm/alpha

2026-04-17T15:34:43+00:00

Pull alpha updates from Magnus Lindholm: "One fix to silence pgprot_modify() compiler warnings, and one patch adding SECCOMP/SECCOMP_FILTER support together with the syscall and ptrace fixes needed for it" * tag 'alpha-for-v7.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/lindholm/alpha: alpha: Define pgprot_modify to silence tautological comparison warnings alpha: add support for SECCOMP and SECCOMP_FILTER

alpha: add support for SECCOMP and SECCOMP_FILTER

2026-04-12T17:13:59+00:00

Add SECCOMP and SECCOMP_FILTER support to the Alpha architecture and fix syscall entry and ptrace issues uncovered by the seccomp-bpf selftests. The syscall entry path is reworked to consistently track syscall state using r0, r1 and r2: - r1 holds the active syscall number - r2 preserves the original syscall number for restart - r0 carries the return value, with r19 (a3) indicating success/error This allows syscall restarts to be permitted only for valid ERESTART* return codes and prevents kernel-internal restart values from leaking to userspace. The syscall tracing error marker is corrected to use the saved syscall number slot, matching the Alpha ABI. Additionally, implement minimal PTRACE_GETREGSET and PTRACE_SETREGSET support for NT_PRSTATUS, exporting struct pt_regs directly. This fixes ptrace-based seccomp tests that previously failed with -EIO. With these changes, seccomp-bpf and ptrace syscall tests pass reliably on Alpha. Tested-by: Michael Cree Signed-off-by: Magnus Lindholm Link: https://lore.kernel.org/r/20260409171439.8759-2-linmag7@gmail.com Signed-off-by: Magnus Lindholm

riscv: enable HAVE_IOREMAP_PROT

2026-04-05T00:42:44+00:00

RISC-V has implemented pte_pgprot() and selects GENERIC_IOREMAP, which provides a generic ioremap_prot() implementation. Enable HAVE_IOREMAP_PROT to activate generic_access_phys() support, which is useful for debugging (e.g., accessing /dev/mem via gdb). Also update the architecture support documentation accordingly. Signed-off-by: Yufeng Wang Link: https://patch.msgid.link/20260306112734.108186-1-r4o5m6e8o@163.com Signed-off-by: Paul Walmsley

documentation: update arch features

2026-02-23T21:40:56+00:00

PA-RISC has perf-event support since commit 610cb23bcc75 ("parisc: Add initial kernel-side perf_event support"); and s390 has stackprotector support since commit f5730d44e05e ("s390: Add stackprotector support"). Signed-off-by: Miquel Sabaté Solà Signed-off-by: Jonathan Corbet Message-ID: <20260219234040.3260616-1-mssola@mssola.com>

s390: Document s390 stackprotector support

2026-02-03T11:48:27+00:00

Recently [1] s390 got stackprotector support. Document this. [1] commit f5730d44e05e ("s390: Add stackprotector support") Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens

Merge tag 'uml-for-linux-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

2025-12-06T00:30:56+00:00

Pull UML updates from Johannes Berg: "Apart from the usual small churn, we have - initial SMP support (only kernel) - major vDSO cleanups (and fixes for 32-bit)" * tag 'uml-for-linux-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (33 commits) um: Disable KASAN_INLINE when STATIC_LINK is selected um: Don't rename vmap to kernel_vmap um: drivers: virtio: use string choices helper um: Always set up AT_HWCAP and AT_PLATFORM x86/um: Remove FIXADDR_USER_START and FIXADDR_USE_END um: Remove __access_ok_vsyscall() um: Remove redundant range check from __access_ok_vsyscall() um: Remove fixaddr_user_init() x86/um: Drop gate area handling x86/um: Do not inherit vDSO from host um: Split out default elf_aux_hwcap x86/um: Move ELF_PLATFORM fallback to x86-specific code um: Split out default elf_aux_platform um: Avoid circular dependency on asm-offsets in pgtable.h um: Enable SMP support on x86 asm-generic: percpu: Add assembly guard um: vdso: Remove getcpu support on x86 um: Add initial SMP support um: Define timers on a per-CPU basis um: Determine sleep based on need_resched() ...

docs: Move the "features" tools to tools/docs

2025-10-28T22:01:00+00:00

The scripts for managing the features docs are found in three different directories; unite them all under tools/docs and update references as needed. Reviewed-by: Mauro Carvalho Chehab Acked-by: Jani Nikula Signed-off-by: Jonathan Corbet

um: Add initial SMP support

2025-10-27T15:41:15+00:00

Add initial symmetric multi-processing (SMP) support to UML. With this support enabled, users can tell UML to start multiple virtual processors, each represented as a separate host thread. In UML, kthreads and normal threads (when running in kernel mode) can be scheduled and executed simultaneously on different virtual processors. However, the userspace code of normal threads still runs within their respective single-threaded stubs. That is, SMP support is currently available both within the kernel and across different processes, but still remains limited within threads of the same process in userspace. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-6-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

Merge tag 'for-linus' of https://github.com/openrisc/linux

2025-10-05T17:02:54+00:00

Pull OpenRISC updates from Stafford Horne: "I picked up one series from Chen Miao, our Google Summer of Code contributor, which adds OpenRISC support for static keys" * tag 'for-linus' of https://github.com/openrisc/linux: openrisc: Add jump label support openrisc: Regenerate defconfigs. openrisc: Add R_OR1K_32_PCREL relocation type module support openrisc: Add text patching API support