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Nathan Chancellor eec08090bc Makefile: Only specify '--prefix=' when building with clang + GNU as
When building with LLVM_IAS=1, there is no point to specifying
'--prefix=' because that flag is only used to find GNU cross tools,
which will not be used indirectly when using the integrated assembler.
All of the tools are invoked directly from PATH or a full path specified
via the command line, which does not depend on the value of '--prefix='.

Sharing commands to reproduce issues becomes a little bit easier without
a '--prefix=' value because that '--prefix=' value is specific to a
user's machine due to it being an absolute path.

Some further notes from Fangrui Song:

  clang can spawn GNU as (if -f?no-integrated-as is specified) and GNU
  objcopy (-f?no-integrated-as and -gsplit-dwarf and -g[123]).
  objcopy is only used for GNU as assembled object files.
  With integrated assembler, the object file streamer creates .o and
  .dwo simultaneously.
  With GNU as, two objcopy commands are needed to extract .debug*.dwo to
  .dwo files && another command to remove .debug*.dwo sections.

A small consequence of this change (to keep things simple) is that
'--prefix=' will always be specified now, even with a native build, when
it was not before. This should not be an issue due to the way that the
Makefile searches for the prefix (based on elfedit's location). This
ends up improving the experience for host builds because PATH is better
respected and matches GCC's behavior more closely. See the below thread
for more details:

https://lore.kernel.org/r/20210205213651.GA16907@Ryzen-5-4500U.localdomain/

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-04-25 05:13:45 +09:00
Documentation kbuild: add CONFIG_VMLINUX_MAP expert option 2021-04-25 05:12:26 +09:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
arch A set of irqchip updates: 2021-03-14 13:33:33 -07:00
block block: Discard page cache of zone reset target range 2021-03-11 11:49:25 -07:00
certs certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID 2021-01-21 16:16:10 +00:00
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
drivers A set of irqchip updates: 2021-03-14 13:33:33 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
include A set of irqchip updates: 2021-03-14 13:33:33 -07:00
init Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel prctl: fix PR_SET_MM_AUXV kernel stack leak 2021-03-14 14:33:27 -07:00
lib kbuild: add CONFIG_VMLINUX_MAP expert option 2021-04-25 05:12:26 +09:00
mm Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
net NFS Client Bugfixes for Linux 5.10-rc3 2021-03-12 14:19:35 -08:00
samples Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
scripts kbuild: move $(strip ) to suffix-search definition 2021-04-25 05:12:42 +09:00
security Revert 95ebabde38 ("capabilities: Don't allow writing ambiguous v3 file capabilities") 2021-03-12 15:27:14 -06:00
sound ALSA: hda/hdmi: Cancel pending works before suspend 2021-03-10 12:52:01 +01:00
tools A single objtool fix to handle the PUSHF/POPF validation correctly for the 2021-03-14 13:15:55 -07:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: add CONFIG_VMLINUX_MAP expert option 2021-04-25 05:12:26 +09:00
.mailmap treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2021-03-14 12:23:34 -07:00
Makefile Makefile: Only specify '--prefix=' when building with clang + GNU as 2021-04-25 05:13:45 +09:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.