From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- Documentation/networking/mpls-sysctl.rst | 57 ++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 Documentation/networking/mpls-sysctl.rst (limited to 'Documentation/networking/mpls-sysctl.rst') diff --git a/Documentation/networking/mpls-sysctl.rst b/Documentation/networking/mpls-sysctl.rst new file mode 100644 index 000000000..0a2ac8840 --- /dev/null +++ b/Documentation/networking/mpls-sysctl.rst @@ -0,0 +1,57 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================== +MPLS Sysfs variables +==================== + +/proc/sys/net/mpls/* Variables: +=============================== + +platform_labels - INTEGER + Number of entries in the platform label table. It is not + possible to configure forwarding for label values equal to or + greater than the number of platform labels. + + A dense utilization of the entries in the platform label table + is possible and expected as the platform labels are locally + allocated. + + If the number of platform label table entries is set to 0 no + label will be recognized by the kernel and mpls forwarding + will be disabled. + + Reducing this value will remove all label routing entries that + no longer fit in the table. + + Possible values: 0 - 1048575 + + Default: 0 + +ip_ttl_propagate - BOOL + Control whether TTL is propagated from the IPv4/IPv6 header to + the MPLS header on imposing labels and propagated from the + MPLS header to the IPv4/IPv6 header on popping the last label. + + If disabled, the MPLS transport network will appear as a + single hop to transit traffic. + + * 0 - disabled / RFC 3443 [Short] Pipe Model + * 1 - enabled / RFC 3443 Uniform Model (default) + +default_ttl - INTEGER + Default TTL value to use for MPLS packets where it cannot be + propagated from an IP header, either because one isn't present + or ip_ttl_propagate has been disabled. + + Possible values: 1 - 255 + + Default: 255 + +conf//input - BOOL + Control whether packets can be input on this interface. + + If disabled, packets will be discarded without further + processing. + + * 0 - disabled (default) + * not 0 - enabled -- cgit v1.3.1