dda2bc8289
[ Upstream commit 8abe7fc26ad8f28bfdf78adbed56acd1fa93f82d ] When cross-compiling with Clang, the `$(CLANG_FLAGS)' variable contains additional flags needed to build C and assembly sources for the target platform. Normally this variable is automatically included in `$(KBUILD_CFLAGS)' via the top-level Makefile. The x86 real-mode makefile builds `$(REALMODE_CFLAGS)' from a plain assignment and therefore drops the Clang flags. This causes Clang to not recognize x86-specific assembler directives: arch/x86/realmode/rm/header.S:36:1: error: unknown directive .type real_mode_header STT_OBJECT ; .size real_mode_header, .-real_mode_header ^ Explicit propagation of `$(CLANG_FLAGS)' to `$(REALMODE_CFLAGS)', which is inherited by real-mode make rules, fixes cross-compilation with Clang for x86 targets. Relevant flags: * `--target' sets the target architecture when cross-compiling. This flag must be set for both compilation and assembly (`KBUILD_AFLAGS') to support architecture-specific assembler directives. * `-no-integrated-as' tells clang to assemble with GNU Assembler instead of its built-in LLVM assembler. This flag is set by default unless `LLVM_IAS=1' is set, because the LLVM assembler can't yet parse certain GNU extensions. Signed-off-by: John Millikin <john@john-millikin.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Link: https://lkml.kernel.org/r/20210326000435.4785-2-nathan@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.