compile_commands.json: add clang.excludeArgs for Linux

Getting-started.md

@@ -99,6 +99,15 @@ If your project is compiled with MSVC, you may change the compiler driver (`%cla
 
 See https://clang.llvm.org/docs/MSVCCompatibility.html
 
+### Standalone mode
+
+ccls indexer can be used standalone. The following command indexes the project and creates `~/llvm/.ccls-cache/`.
+If you have `clang.extraArgs`, make sure your client uses the same initialization option, otherwise cflags mismatch will cause re-indexing.
+
+```zsh
+ccls -index ~/llvm -init='{"clang":{"extraArgs": ["--gcc-toolchain=/usr"]}}'
+```
+
 ### Cases
 
 On a laptop with one (i7-6600U CPU @ 2.60GHz, hyper-threading, `nproc`=4), 4 indexers.

compile_commands.json.md

@@ -114,6 +114,14 @@ yes '' | make config
 bear make -j bzImage modules
 ```
 
+```zsh
+ccls -index ~/Dev/Linux -init='{"clang":{"excludeArgs":[
+"-falign-jumps=1","-falign-loops=1","-fconserve-stack","-fmerge-constants","-fno-code-hoisting","-fno-schedule-insns","-fno-var-tracking-assignments",
+"-mhard-float","-mindirect-branch-register","-mindirect-branch=thunk-inline","-mpreferred-stack-boundary=2","-mpreferred-stack-boundary=3","-mpreferred-stack-boundary=4","-mrecord-mcount","-mindirect-branch=thunk-extern","-mno-fp-ret-in-387","-mskip-rax-setup",
+"--param=allow-store-data-races=0","-Wa,arch/x86/kernel/macros.s","-Wa,-"
+], "extraArgs":["--gcc-toolchain=/usr"]}}'
+```
+
 ### musl
 
 ```zsh