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Diffstat (limited to 'Documentation/bpf/bpf_devel_QA.rst')
| -rw-r--r-- | Documentation/bpf/bpf_devel_QA.rst | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/Documentation/bpf/bpf_devel_QA.rst b/Documentation/bpf/bpf_devel_QA.rst index de27e1620821..45bc5c5cd793 100644 --- a/Documentation/bpf/bpf_devel_QA.rst +++ b/Documentation/bpf/bpf_devel_QA.rst @@ -382,6 +382,14 @@ In case of new BPF instructions, once the changes have been accepted into the Linux kernel, please implement support into LLVM's BPF back end. See LLVM_ section below for further information. +Q: What "BPF_INTERNAL" symbol namespace is for? +----------------------------------------------- +A: Symbols exported as BPF_INTERNAL can only be used by BPF infrastructure +like preload kernel modules with light skeleton. Most symbols outside +of BPF_INTERNAL are not expected to be used by code outside of BPF either. +Symbols may lack the designation because they predate the namespaces, +or due to an oversight. + Stable submission ================= @@ -603,9 +611,10 @@ Q: I have added a new BPF instruction to the kernel, how can I integrate it into LLVM? A: LLVM has a ``-mcpu`` selector for the BPF back end in order to allow -the selection of BPF instruction set extensions. By default the -``generic`` processor target is used, which is the base instruction set -(v1) of BPF. +the selection of BPF instruction set extensions. Before llvm version 20, +the ``generic`` processor target is used, which is the base instruction +set (v1) of BPF. Since llvm 20, the default processor target has changed +to instruction set v3. LLVM has an option to select ``-mcpu=probe`` where it will probe the host kernel for supported BPF instruction set extensions and selects the |