Based on a vote at the LLVM BoF at Plumbers 2020, we decided to start
small, supporting just one formal upstream release of LLVM for now.

We can probably widen the support window of supported versions over
time.  Also, note that LLVM's release process is different than GCC's.
GCC tends to have 1 major release per year while releasing minor updates
to the past 3 major versions.  LLVM tends to support one major release
and one minor release every six months.
Signed-off-by: NNick Desaulniers <ndesaulniers@google.com>
Tested-by: NGustavo A. R. Silva <gustavoars@kernel.org>
Tested-by: NNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: NMasahiro Yamada <masahiroy@kernel.org>
Acked-by: NWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200826191555.3350406-1-ndesaulniers@google.comSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Update Documentation for the gcc v4.9 upgrade requirement.

Fixes: 5429ef62 ("compiler/gcc: Raise minimum GCC version for kernel builds to 4.8")
Fixes: 6ec4476a ("Raise gcc version requirement to 4.9")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Acked-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
          If both the HTTP and HTTPS versions
          return 200 OK and serve the same content:
            Replace HTTP with HTTPS.
Signed-off-by: NAlexander A. Klimov <grandmaster@al2klimov.de>
Acked-by: NMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/r/20200621133630.46435-1-grandmaster@al2klimov.deSigned-off-by: NJonathan Corbet <corbet@lwn.net>

It is very rare to see versions of GCC prior to 4.8 being used to build
the mainline kernel. These old compilers are also know to have codegen
issues which can lead to silent miscompilation:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145

Raise the minimum GCC version for kernel build to 4.8 and remove some
tautological Kconfig dependencies as a consequence.

Cc: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NWill Deacon <will@kernel.org>

The currently minimum-supported binutils version 2.21 has the problem of
promoting symbols which are defined outside of a section into absolute.
According to Arvind:

  binutils-2.21 and -2.22. An x86-64 defconfig will fail with
          Invalid absolute R_X86_64_32S relocation: _etext
  and after fixing that one, with
          Invalid absolute R_X86_64_32S relocation: __end_of_kernel_reserve

Those two versions of binutils have a bug when it comes to handling
symbols defined outside of a section and binutils 2.23 has the proper
fix, see: https://sourceware.org/legacy-ml/binutils/2012-06/msg00155.html

Therefore, up to the fixed version directly, skipping the broken ones.

Currently shipping distros already have the fixed binutils version so
there should be no breakage resulting from this.

For more details about the whole thing, see the thread in Link.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200110202349.1881840-1-nivedita@alum.mit.eduAcked-by: NKees Cook <keescook@chromium.org>
Acked-by: NJason A. Donenfeld <Jason@zx2c4.com>
Acked-by: NNick Desaulniers <ndesaulniers@google.com>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>

Update projects URLs in the changes.rst file.
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Acked-by: NTheodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/a9c3c509-8f30-fcc4-d9e0-b53aeaa89e4f@infradead.orgSigned-off-by: NJonathan Corbet <corbet@lwn.net>

It helps to use some new instructions directly in assembly code.
Suggested-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Linux Torvalds <torvalds@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lkml.kernel.org/r/1557309753-24073-5-git-send-email-chang.seok.bae@intel.com

With all isdn4linux hardware drivers gone, this is only a wrapper around
CAPI to support old user space. However, from looking at the mailing
list, it seems that the last time anyone asked about it was in 2014,
when the upgrade from a linux-2.4 installation failed, and mISDN was
suggested as a replacement.

The largest public ISDN network (Deutsche Telekom) was supposed to be
shut down 2018, which must have drastically reduced the number of legacy
installations.

When we last discussed removing i4l in 2016, Karsten Keil suggested
revisiting this in 2018. I guess this is overdue.

Link: http://listserv.isdn4linux.de/pipermail/isdn4linux/2014-October/006165.html
Link: https://patchwork.kernel.org/patch/8484861/#17900371
Link: https://listserv.isdn4linux.de/pipermail/isdn4linux/2019-April/thread.htmlSigned-off-by: NArnd Bergmann <arnd@arndb.de>

Some documents are refering to others without links. With this
patch I add those missing links.

This patch affects only documents under process/ and labels where
necessary.
Signed-off-by: NFederico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Meelis Roos reported a {menu,n}config regression:
 "I have libncurses devel package installed in the default system
  location (as do 99%+ on actual developers probably) and in this
  case, pkg-config is useless.  pkg-config is needed only when
  libraries and headers are installed in non-default locations but
  it is bad to require installation of pkg-config on all the machines
  where make menuconfig would be possibly run."

For {menu,n}config, do not use pkg-config if it is not installed.
For {g,x}config, keep checking pkg-config since we really rely on it
for finding the installation paths of the required packages.

Fixes: 4ab3b801 ("kconfig: check for pkg-config on make {menu,n,g,x}config")
Reported-by: NMeelis Roos <mroos@linux.ee>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: NMeelis Roos <mroos@linux.ee>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>

Various architectures fail to build properly with older versions of the
gcc compiler.

An example from Guenter Roeck in thread [1]:
>
>   In file included from ./include/linux/mm.h:17:0,
>                    from ./include/linux/pid_namespace.h:7,
>                    from ./include/linux/ptrace.h:10,
>                    from arch/openrisc/kernel/asm-offsets.c:32:
>   ./include/linux/mm_types.h:497:16: error: flexible array member in otherwise empty struct
>
> This is just an example with gcc 4.5.1 for or32. I have seen the problem
> with gcc 4.4 (for unicore32) as well.

So update the minimum required version of gcc to 4.6.

[1] https://lore.kernel.org/lkml/20180814170904.GA12768@roeck-us.net/

Miscellanea:

 - Update Documentation/process/changes.rst

 - Remove and consolidate version test blocks in compiler-gcc.h for
   versions lower than 4.6
Signed-off-by: NJoe Perches <joe@perches.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Each of 'make {menu,n,g,x}config' uses (needs) pkg-config to make sure
that other required files are present and to determine build flags
settings, but none of these check that pkg-config itself is present.
Add a check for all 4 of these targets and update
Documentation/process/changes.rst to mention 'pkg-config'.

Fixes kernel bugzilla #77511:
https://bugzilla.kernel.org/show_bug.cgi?id=77511Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Bjørn Forsman <bjorn.forsman@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Verify that 'depmod' ($DEPMOD) is installed.
This is a partial revert of commit 620c231c
("kbuild: do not check for ancient modutils tools").

Also update Documentation/process/changes.rst to refer to
kmod instead of module-init-tools.

Fixes kernel bugzilla #198965:
https://bugzilla.kernel.org/show_bug.cgi?id=198965Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Chih-Wei Huang <cwhuang@linux.org.tw>
Cc: stable@vger.kernel.org # any kernel since 2012
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

According to the old project site, https://sourceforge.net/projects/fuse/
the project has moved to https://github.com/libfuse/ so we update the
link to point to the latest libfuse release.
Signed-off-by: NMartin Kepplinger <martink@posteo.de>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Incremental linking is gone, so rename built-in.o to built-in.a, which
is the usual extension for archive files.

This patch does two things, first is a simple search/replace:

git grep -l 'built-in\.o' | xargs sed -i 's/built-in\.o/built-in\.a/g'

The second is to invert nesting of nested text manipulations to avoid
filtering built-in.a out from libs-y2:

-libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.a, $(libs-y)))
+libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

In Linux build system convention, pre-generated files are version-
controlled with a "_shipped" suffix.  During the kernel building,
they are simply shipped (copied) removing the suffix.

This approach can reduce external tool dependency for the kernel build,
but it is tedious to manually regenerate such artifacts from developers'
point of view.  (We need to do "make REGENERATE_PARSERS=1" every time
we touch real source files such as *.l, *.y)

Some months ago, I sent out RFC patches to run flex, bison, and gperf
during the build.

In the review and test, Linus noticed gperf-3.1 had changed the lookup
function prototype.  Then, the use of gperf in kernel was entirely
removed by commit bb3290d9 ("Remove gperf usage from toolchain").

This time, I tested several versions of flex and bison, and I was not
hit by any compatibility issue except a flaw in flex-2.6.3; if you
generate lexer for dtc and genksyms with flex-2.6.3, you will see
"yywrap redefined" warning.  This was not intentional, but a bug,
fixed by flex-2.6.4.  Otherwise, both flex and bison look fairly
stable for a long time.

This commit prepares some build rules to remove the _shipped files.
Also, document minimal requirement for flex and bison.

Rationale for the minimal version:
The -Wmissing-prototypes option of GCC warns "no previous prototype"
for lexers generated by flex-2.5.34 or older, so I chose 2.5.35 as the
required version for flex.  Flex-2.5.35 was released in 2008.  Bison
looks more stable.  I did not see any problem with bison-2.0, released
in 2004.  I did not test bison-1.x, but bison-2.0 should be old enough.

Tested flex versions:
  2.5.35
  2.5.36
  2.5.37
  2.5.39
  2.6.0
  2.6.1
  2.6.2
  2.6.3   (*)
  2.6.4

 (*) flex-2.6.3 causes "yywrap redefined" warning

Tested bison versions:
  2.0
  2.1
  2.2
  2.3
  2.4
  2.4.1
  2.5.1
  2.6
  2.6.1
  2.6.2
  2.6.3
  2.6.4
  2.6.5
  2.7
  2.7.1
  3.0
  3.0.1
  3.0.2
  3.0.3
  3.0.4
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The toolchain used by Sphinx is somewhat complex, and installing
it should be part of the doc-guide.

Move it out of changes.rst.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

The kfigure module doesn't work with Sphinx version 1.2. So,
update the minimal requirements accordingly.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Make thin archives build the default, but keep the config option
to allow exemptions if any breakage can't be quickly solved.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

DocBook is mentioned several times at the documentation. Update
the obsolete references from it at the DocBook.
Acked-by: NSeongJae Park <sj38.park@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

Commit 37d69ee3 ("docs: bump minimal GNU Make version to 3.81")
changes one entry of GNU make version in the changes.rst, there's still
one more entry saying that one need version 3.80.  Fix that.
Signed-off-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since 2014, you can't successfully build kernels with GNU Make version
3.80. Example errors:

  $ git describe
  v4.11
  $ make --version | head -1
  GNU Make 3.80
  $ make defconfig
    HOSTCC  scripts/basic/fixdep
  scripts/Makefile.host:135: *** missing separator.  Stop.
  make: *** [defconfig] Error 2
  $ make ARCH=arm64 help
  arch/arm64/Makefile:43: *** unterminated call to function `warning': missing `)'.  Stop.
  $ make help >/dev/null
  ./Documentation/Makefile.sphinx:25: Extraneous text after `else' directive
  ./Documentation/Makefile.sphinx:31: *** only one `else' per conditional.  Stop.
  make: *** [help] Error 2

The first breakage was introduced by commit c8589d1e ("kbuild:
handle multi-objs dependency appropriately").  Since then (i.e. v3.18),
GNU Make 3.80 has not been able to compile the kernel, but nobody has
ever complained aboutt (or noticed) it.

Even GNU Make 3.81 is more than 10 years old.  It would not hurt to
match the documentation with reality instead of fixing makefiles.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As ftp.kernel.org is closed [0], this commit fixes dead URLs in
documents to use www.kernel.org instead.

[0] https://www.kernel.org/shutting-down-ftp-services.htmlSigned-off-by: NSeongJae Park <sj38.park@gmail.com>
Acked-by: NTheodore Ts'o <tytso@mit.edu>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Reviewed-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

This patch brings scalable figure, image handling and a concept to
embed *render* markups:

* DOT (http://www.graphviz.org)
* SVG

For image handling use the 'image' replacement::

    .. kernel-image::  svg_image.svg
       :alt:    simple SVG image

For figure handling use the 'figure' replacement::

    .. kernel-figure::  svg_image.svg
       :alt:    simple SVG image

       SVG image example

Embed *render* markups (or languages) like Graphviz's **DOT** is
provided by the *render* directive.::

  .. kernel-render:: DOT
     :alt: foobar digraph
     :caption: Embedded **DOT** (Graphviz) code.

     digraph foo {
      "bar" -> "baz";
     }

The *render* directive is a concept to integrate *render* markups and
languages, yet supported markups:

* DOT: render embedded Graphviz's **DOT**
* SVG: render embedded Scalable Vector Graphics (**SVG**)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Tested-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> (v2 - v5)
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de> (v1, v6)
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Put like documents together, with the essential ones at the top, and split
the TOC into sections.
Reviewed-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Add several documents to the development-process ReST book.

As we don't want renames, use symlinks instead, keeping those
documents on their original place.
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

Mauro's patch set introduced some bare :: lines; these can be represented
by a double colon at the end of the preceding text line.  The result looks
a little less weird and is less verbose.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Add cross references for the documents mentioned at HOWTO and
are under the Documentation/ directory, using the ReST notation.

It should be noticed that HOWTO also mentions the /README file.
We opted to not touch it, for now, as making it build on
Sphinx would require it to be moved to a Documentation/foo
directory.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

As discussed at linux-doc ML, the best is to keep all documents
backward compatible with Sphinx version 1.2, as it is the latest
version found on some distros like Debian.

All books currently support it.

Please notice that, while it mentions the eventual need of
XeLaTex and texlive to build pdf files, this is not a minimal
requirement, as one could just be interested on building html
documents. Also, identifying the minimal requirements for
texlive packages is not trivial, as each distribution seems to
use different criteria on grouping LaTex functionalities.

While here, update the current kernel version to 4.x.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

- Fix chapter identation inconsistencies;
- Convert table to ReST format;
- use the right tag for bullets;
- Fix bold emphasis;
- mark blocks with :: tags;
- use verbatim font for files;
- make Sphinx happy
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

bc is mentioned lower in a dedicated section.
Yet it is useful to have all dependencies listed in
"Current Minimal Requirements" section.
Signed-off-by: NBenoit Lemarchand <benoit.lemarchand@gmail.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

The sign-file.c program actually uses CMS rather than PKCS#7 to sign a file
since that allows the target X.509 certificate to be specified by
subjectKeyId rather than by issuer + serialNumber.

However, older versions of the OpenSSL crypto library (such as may be found
in CentOS 5.11) don't support CMS.  Assume everything prior to
OpenSSL-1.0.0 doesn't support CMS and switch to using PKCS#7 in that case.

Further, the pre-1.0.0 OpenSSL only supports PKCS#7 signing with SHA1, so
give an error from the sign-file script if the caller requests anything
other than SHA1.

The compiler gives the following error with an OpenSSL crypto library
that's too old:

  HOSTCC  scripts/sign-file
scripts/sign-file.c:23:25: fatal error: openssl/cms.h: No such file or directory
 #include <openssl/cms.h>
Reported-by: NVinson Lee <vlee@twopensource.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NDavid Woodhouse <David.Woodhouse@intel.com>

The module signing script (sign-file) used to be a wrapper around the
openssl program.  It has now been replaced by a C program that uses the
crypto library from the OpenSSL package meaning that the OpenSSL devel
packages are necessary to provide the devel library link and the header
files.

This would be openssl-devel on Fedora and libssl-dev on Debian.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>

The official spelling of GNU is GNU and not Gnu.
Bug 89551 https://bugzilla.kernel.org/show_bug.cgi?id=89551Signed-off-by: NKevin Law <kevin@stealsyour.pw>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Signed-off-by: NAndrew Shewmaker <agshew@gmail.com>
Acked-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

remove pcmcia-cs from Changes, since it seems to be obsolete since a long time
Signed-off-by: NSimon Danner <danner.simon@gmail.com>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Update broken links in Changes
Signed-off-by: NSimon Danner <danner.simon@gmail.com>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

The paragraph on mcelog currently describes kernel v2.6.31. In that
kernel the mce code (for i386, that is) was in transition. Ever since
v2.6.32 the situation is much simpler (eg, mcelog is now needed to
process events on almost all x86 machines, i386 and x86-64). Since this
"document is designed to provide a list of the minimum levels of
software necessary to run the 3.0 kernels" let's just describe that
situation.
Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Acked-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

HPA did the world a favour and reduced the number of perl scripts in the
universe. However we do now need bc

Resolves-bug: https://bugzilla.kernel.org/show_bug.cgi?id=60575Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This tool hasn't been maintained in over a decade, and is pretty much
useless these days.  Let's pretend it never happened.

Also remove a long-dead email address.
Signed-off-by: NDave Jones <davej@fedoraproject.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>