linux-toradex.git/Documentation/admin-guide/kernel-parameters.rst, branch v5.17-rc4

bitmap_parse: Support 'all' semantics

2021-05-10T22:38:20+00:00

RCU code supports an 'all' group as a special case when parsing rcu_nocbs
parameter. This patch moves the 'all' support to the core bitmap_parse
code, so that all bitmap users can enjoy this extension.

Moving 'all' parsing to a bitmap_parse level also allows users to pass
patterns together with 'all' in regular group:pattern format, for example,
"rcu_nocbs=all:1/2" would offload all the even-numbered CPUs regardless
of the number of CPUs on the system.

Reviewed-by: Andy Shevchenko 
Signed-off-by: Yury Norov 
Signed-off-by: Paul E. McKenney

Merge tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2021-04-28T19:00:13+00:00

Pull RCU updates from Ingo Molnar:

 - Support for "N" as alias for last bit in bitmap parsing library (eg
   using syntax like "nohz_full=2-N")

 - kvfree_rcu updates

 - mm_dump_obj() updates. (One of these is to mm, but was suggested by
   Andrew Morton.)

 - RCU callback offloading update

 - Polling RCU grace-period interfaces

 - Realtime-related RCU updates

 - Tasks-RCU updates

 - Torture-test updates

 - Torture-test scripting updates

 - Miscellaneous fixes

* tag 'core-rcu-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits)
  rcutorture: Test start_poll_synchronize_rcu() and poll_state_synchronize_rcu()
  rcu: Provide polling interfaces for Tiny RCU grace periods
  torture: Fix kvm.sh --datestamp regex check
  torture: Consolidate qemu-cmd duration editing into kvm-transform.sh
  torture: Print proper vmlinux path for kvm-again.sh runs
  torture: Make TORTURE_TRUST_MAKE available in kvm-again.sh environment
  torture: Make kvm-transform.sh update jitter commands
  torture: Add --duration argument to kvm-again.sh
  torture: Add kvm-again.sh to rerun a previous torture-test
  torture: Create a "batches" file for build reuse
  torture: De-capitalize TORTURE_SUITE
  torture: Make upper-case-only no-dot no-slash scenario names official
  torture: Rename SRCU-t and SRCU-u to avoid lowercase characters
  torture: Remove no-mpstat error message
  torture: Record kvm-test-1-run.sh and kvm-test-1-run-qemu.sh PIDs
  torture: Record jitter start/stop commands
  torture: Extract kvm-test-1-run-qemu.sh from kvm-test-1-run.sh
  torture: Record TORTURE_KCONFIG_GDB_ARG in qemu-cmd
  torture: Abstract jitter.sh start/stop into scripts
  rcu: Provide polling interfaces for Tree RCU grace periods
  ...

Documentation/admin-guide: kernel-parameters: correct the architectures for numa_balancing

2021-03-09T00:19:05+00:00

X86 isn't the only architecture supporting NUMA_BALANCING. ARM64, PPC,
S390 and RISCV also support it:

arch$ git grep NUMA_BALANCING
arm64/Kconfig:  select ARCH_SUPPORTS_NUMA_BALANCING
arm64/configs/defconfig:CONFIG_NUMA_BALANCING=y
arm64/include/asm/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
powerpc/configs/powernv_defconfig:CONFIG_NUMA_BALANCING=y
powerpc/configs/ppc64_defconfig:CONFIG_NUMA_BALANCING=y
powerpc/configs/pseries_defconfig:CONFIG_NUMA_BALANCING=y
powerpc/include/asm/book3s/64/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
powerpc/include/asm/book3s/64/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
powerpc/include/asm/book3s/64/pgtable.h:#endif /* CONFIG_NUMA_BALANCING */
powerpc/include/asm/book3s/64/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
powerpc/include/asm/book3s/64/pgtable.h:#endif /* CONFIG_NUMA_BALANCING */
powerpc/include/asm/nohash/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
powerpc/include/asm/nohash/pgtable.h:#endif /* CONFIG_NUMA_BALANCING */
powerpc/platforms/Kconfig.cputype:      select ARCH_SUPPORTS_NUMA_BALANCING
riscv/Kconfig:  select ARCH_SUPPORTS_NUMA_BALANCING
riscv/include/asm/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
s390/Kconfig:   select ARCH_SUPPORTS_NUMA_BALANCING
s390/configs/debug_defconfig:CONFIG_NUMA_BALANCING=y
s390/configs/defconfig:CONFIG_NUMA_BALANCING=y
s390/include/asm/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
x86/Kconfig:    select ARCH_SUPPORTS_NUMA_BALANCING     if X86_64
x86/include/asm/pgtable.h:#ifdef CONFIG_NUMA_BALANCING
x86/include/asm/pgtable.h:#endif /* CONFIG_NUMA_BALANCING */

On the other hand, setup_numabalancing() is implemented in mm/mempolicy.c
which doesn't depend on architectures.

Signed-off-by: Barry Song 
Reviewed-by: Palmer Dabbelt 
Acked-by: Palmer Dabbelt 
Cc: Mel Gorman 
Cc: Paul Walmsley 
Cc: Palmer Dabbelt 
Cc: Albert Ou 
Cc: "Paul E. McKenney" 
Cc: Randy Dunlap 
Cc: Andrew Morton 
Cc: Thomas Gleixner 
Cc: Mauro Carvalho Chehab 
Cc: Viresh Kumar 
Cc: Mike Kravetz 
Cc: Peter Zijlstra 
Link: https://lore.kernel.org/r/20210302084159.33688-1-song.bao.hua@hisilicon.com
Signed-off-by: Jonathan Corbet

lib: bitmap: support "N" as an alias for size of bitmap

2021-03-08T22:16:58+00:00

While this is done for all bitmaps, the original use case in mind was
for CPU masks and cpulist_parse() as described below.

It seems that a common configuration is to use the 1st couple cores for
housekeeping tasks.  This tends to leave the remaining ones to form a
pool of similarly configured cores to take on the real workload of
interest to the user.

So on machine A - with 32 cores, it could be 0-3 for "system" and then
4-31 being used in boot args like nohz_full=, or rcu_nocbs= as part of
setting up the worker pool of CPUs.

But then newer machine B is added, and it has 48 cores, and so while
the 0-3 part remains unchanged, the pool setup cpu list becomes 4-47.

Multiple deployment becomes easier when we can just simply replace 31
and 47 with "N" and let the system substitute in the actual number at
boot; a number that it knows better than we do.

Cc: Yury Norov 
Cc: Peter Zijlstra 
Cc: "Paul E. McKenney" 
Cc: Rasmus Villemoes 
Cc: Andy Shevchenko 
Suggested-by: Yury Norov  # move it from CPU code
Acked-by: Yury Norov 
Signed-off-by: Paul Gortmaker 
Signed-off-by: Paul E. McKenney

Documentation: kernel-parameters: add missing '<'

2021-01-28T22:24:06+00:00

Acked-by: Randy Dunlap 
Signed-off-by: Wolfram Sang 
Link: https://lore.kernel.org/r/20210127104343.5647-1-wsa+renesas@sang-engineering.com
Signed-off-by: Jonathan Corbet

Documentation: admin: early_param()s are also listed in kernel-parameters

2020-12-31T22:46:18+00:00

Add info that "early_param()" kernel boot parameters are also listed
in kernel-parameters.txt.

Signed-off-by: Randy Dunlap 
Cc: Jonathan Corbet 
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/20201226174433.7885-1-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet

Documentation/admin-guide: mark memmap parameter is supported by a few architectures

2020-11-30T17:35:32+00:00

early_param memmap is only implemented on X86, MIPS and XTENSA. To avoid
wasting users’ time on trying this on platform like ARM, mark it clearly.

Signed-off-by: Barry Song 
Reviewed-by: Mike Rapoport 
Link: https://lore.kernel.org/r/20201128195121.2556-1-song.bao.hua@hisilicon.com
Signed-off-by: Jonathan Corbet

of: property: Add functional dependency link from DT bindings

2019-10-04T15:29:50+00:00

Add device links after the devices are created (but before they are
probed) by looking at common DT bindings like clocks and
interconnects.

Automatically adding device links for functional dependencies at the
framework level provides the following benefits:

- Optimizes device probe order and avoids the useless work of
  attempting probes of devices that will not probe successfully
  (because their suppliers aren't present or haven't probed yet).

  For example, in a commonly available mobile SoC, registering just
  one consumer device's driver at an initcall level earlier than the
  supplier device's driver causes 11 failed probe attempts before the
  consumer device probes successfully. This was with a kernel with all
  the drivers statically compiled in. This problem gets a lot worse if
  all the drivers are loaded as modules without direct symbol
  dependencies.

- Supplier devices like clock providers, interconnect providers, etc
  need to keep the resources they provide active and at a particular
  state(s) during boot up even if their current set of consumers don't
  request the resource to be active. This is because the rest of the
  consumers might not have probed yet and turning off the resource
  before all the consumers have probed could lead to a hang or
  undesired user experience.

  Some frameworks (Eg: regulator) handle this today by turning off
  "unused" resources at late_initcall_sync and hoping all the devices
  have probed by then. This is not a valid assumption for systems with
  loadable modules. Other frameworks (Eg: clock) just don't handle
  this due to the lack of a clear signal for when they can turn off
  resources. This leads to downstream hacks to handle cases like this
  that can easily be solved in the upstream kernel.

  By linking devices before they are probed, we give suppliers a clear
  count of the number of dependent consumers. Once all of the
  consumers are active, the suppliers can turn off the unused
  resources without making assumptions about the number of consumers.

By default we just add device-links to track "driver presence" (probe
succeeded) of the supplier device. If any other functionality provided
by device-links are needed, it is left to the consumer/supplier
devices to change the link when they probe.

kbuild test robot reported clang error about missing const
Reported-by: kbuild test robot 
Signed-off-by: Saravana Kannan 
Link: https://lore.kernel.org/r/20190904211126.47518-4-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman

docs: m68k: convert docs to ReST and rename to *.rst

2019-07-15T12:20:23+00:00

Convert the m68k kernel-options.txt file to ReST.

The conversion is trivial, as the document is already on a format
close enough to ReST. Just some small adjustments were needed in
order to make it both good for being parsed while keeping it on
a good txt shape.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab

docs: format kernel-parameters -- as code

2019-06-28T15:06:14+00:00

The current ReStructuredText formatting results in "--", used to
indicate the end of the kernel command-line parameters, appearing as
an en-dash instead of two hyphens; this patch formats them as code,
"``--``", as done elsewhere in the documentation.

Signed-off-by: Stephen Kitt 
Signed-off-by: Jonathan Corbet