build: add support for using prebuilt LLVM toolchain

When the prebuilt llvm toolchain is unpacked into the source dir,
it is automatically picked up and used by the build system, and eBPF
based packages can be selected

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/include/bpf.mk b/include/bpf.mk
index 28cdf6cb3235f938077c521b2c0b86e19feb01db..c68ad74554911afa8240c6addc6c26c45167c54f 100644 (file)
--- a/include/bpf.mk
+++ b/include/bpf.mk
@@ -1,6 +1,7 @@
 BPF_DEPENDS := @HAS_BPF_TOOLCHAIN
+LLVM_VER:=
 
-ifneq ($(CONFIG_BPF_TOOLCHAIN_HOST),)
+ifneq ($(CONFIG_USE_LLVM_HOST),)
   BPF_TOOLCHAIN_HOST_PATH:=$(call qstrip,$(CONFIG_BPF_TOOLCHAIN_HOST_PATH))
   ifneq ($(BPF_TOOLCHAIN_HOST_PATH),)
     BPF_PATH:=$(BPF_TOOLCHAIN_HOST_PATH)/bin:$(PATH)
@@ -9,9 +10,12 @@ ifneq ($(CONFIG_BPF_TOOLCHAIN_HOST),)
   endif
   CLANG:=$(firstword $(shell PATH='$(BPF_PATH)' which clang clang-13 clang-12 clang-11))
   LLVM_VER:=$(subst clang,,$(notdir $(CLANG)))
-else
+endif
+ifneq ($(CONFIG_USE_LLVM_PREBUILT),)
+  CLANG:=$(TOPDIR)/llvm-bpf/bin/clang
+endif
+ifneq ($(CONFIG_USE_LLVM_BUILD),)
   CLANG:=$(STAGING_DIR_HOST)/llvm-bpf/bin/clang
-  LLVM_VER:=
 endif
 
 LLVM_PATH:=$(dir $(CLANG))

diff --git a/toolchain/Config.in b/toolchain/Config.in
index a7da2a1f732535d3c1ac56545728ad725860d012..366f5c8b486c462372ae3f1f187a363c249c531e 100644 (file)
--- a/toolchain/Config.in
+++ b/toolchain/Config.in
@@ -41,11 +41,17 @@ menuconfig TARGET_OPTIONS
        choice BPF_TOOLCHAIN
                prompt "BPF toolchain" if DEVEL
                default BPF_TOOLCHAIN_BUILD_LLVM if BUILDBOT
+               default BPF_TOOLCHAIN_PREBUILT if HAS_PREBUILT_LLVM_TOOLCHAIN
                default BPF_TOOLCHAIN_NONE
 
                config BPF_TOOLCHAIN_NONE
                        bool "None"
 
+               config BPF_TOOLCHAIN_PREBUILT
+                       bool "Use prebuilt LLVM toolchain"
+                       depends on HAS_PREBUILT_LLVM_TOOLCHAIN
+                       select USE_LLVM_PREBUILT
+
                config BPF_TOOLCHAIN_HOST
                        select USE_LLVM_HOST
                        bool "Use host LLVM toolchain"
@@ -298,10 +304,18 @@ config GDB_PYTHON
 config HAS_BPF_TOOLCHAIN
        bool
 
+config HAS_PREBUILT_LLVM_TOOLCHAIN
+       def_bool $(shell, [ -f llvm-bpf/.llvm-version ] && echo y || echo n)
+
 config USE_LLVM_HOST
        select HAS_BPF_TOOLCHAIN
        bool
 
+config USE_LLVM_PREBUILT
+       select HAS_BPF_TOOLCHAIN
+       default y if !DEVEL && !BUILDBOT && HAS_PREBUILT_LLVM_TOOLCHAIN
+       bool
+
 config USE_LLVM_BUILD
        default y if !DEVEL && BUILDBOT
        select HAS_BPF_TOOLCHAIN