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-rw-r--r--Documentation/ABI/stable/sysfs-driver-mlxreg-io13
-rw-r--r--Documentation/admin-guide/devices.txt2
-rw-r--r--Documentation/arm64/cpu-feature-registers.rst16
-rw-r--r--Documentation/arm64/elf_hwcaps.rst31
-rw-r--r--Documentation/arm64/silicon-errata.rst2
-rw-r--r--Documentation/core-api/xarray.rst70
-rw-r--r--Documentation/dev-tools/kcov.rst10
-rw-r--r--Documentation/dev-tools/kunit/start.rst13
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-at91.txt6
-rw-r--r--Documentation/devicetree/bindings/net/fsl-fman.txt13
-rw-r--r--Documentation/devicetree/bindings/spi/spi-controller.yaml4
-rw-r--r--Documentation/features/debug/gcov-profile-all/arch-support.txt2
-rw-r--r--Documentation/media/v4l-drivers/meye.rst2
-rw-r--r--Documentation/networking/dsa/sja1105.rst6
-rw-r--r--Documentation/networking/ip-sysctl.txt2
-rw-r--r--Documentation/networking/netdev-FAQ.rst4
-rw-r--r--Documentation/process/embargoed-hardware-issues.rst2
-rw-r--r--Documentation/process/index.rst1
-rw-r--r--Documentation/riscv/index.rst1
-rw-r--r--Documentation/riscv/patch-acceptance.rst35
20 files changed, 175 insertions, 60 deletions
diff --git a/Documentation/ABI/stable/sysfs-driver-mlxreg-io b/Documentation/ABI/stable/sysfs-driver-mlxreg-io
index 8ca498447aeb..05601a90a9b6 100644
--- a/Documentation/ABI/stable/sysfs-driver-mlxreg-io
+++ b/Documentation/ABI/stable/sysfs-driver-mlxreg-io
@@ -29,13 +29,13 @@ Description: This file shows the system fans direction:
The files are read only.
-What: /sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/jtag_enable
+What: /sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/cpld3_version
Date: November 2018
KernelVersion: 5.0
Contact: Vadim Pasternak <vadimpmellanox.com>
Description: These files show with which CPLD versions have been burned
- on LED board.
+ on LED or Gearbox board.
The files are read only.
@@ -121,6 +121,15 @@ Description: These files show the system reset cause, as following: ComEx
The files are read only.
+What: /sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/cpld4_version
+Date: November 2018
+KernelVersion: 5.0
+Contact: Vadim Pasternak <vadimpmellanox.com>
+Description: These files show with which CPLD versions have been burned
+ on LED board.
+
+ The files are read only.
+
Date: June 2019
KernelVersion: 5.3
Contact: Vadim Pasternak <vadimpmellanox.com>
diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt
index 1c5d2281efc9..2a97aaec8b12 100644
--- a/Documentation/admin-guide/devices.txt
+++ b/Documentation/admin-guide/devices.txt
@@ -319,7 +319,7 @@
182 = /dev/perfctr Performance-monitoring counters
183 = /dev/hwrng Generic random number generator
184 = /dev/cpu/microcode CPU microcode update interface
- 186 = /dev/atomicps Atomic shapshot of process state data
+ 186 = /dev/atomicps Atomic snapshot of process state data
187 = /dev/irnet IrNET device
188 = /dev/smbusbios SMBus BIOS
189 = /dev/ussp_ctl User space serial port control
diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst
index b6e44884e3ad..41937a8091aa 100644
--- a/Documentation/arm64/cpu-feature-registers.rst
+++ b/Documentation/arm64/cpu-feature-registers.rst
@@ -117,6 +117,8 @@ infrastructure:
+------------------------------+---------+---------+
| Name | bits | visible |
+------------------------------+---------+---------+
+ | RNDR | [63-60] | y |
+ +------------------------------+---------+---------+
| TS | [55-52] | y |
+------------------------------+---------+---------+
| FHM | [51-48] | y |
@@ -200,6 +202,12 @@ infrastructure:
+------------------------------+---------+---------+
| Name | bits | visible |
+------------------------------+---------+---------+
+ | I8MM | [55-52] | y |
+ +------------------------------+---------+---------+
+ | DGH | [51-48] | y |
+ +------------------------------+---------+---------+
+ | BF16 | [47-44] | y |
+ +------------------------------+---------+---------+
| SB | [39-36] | y |
+------------------------------+---------+---------+
| FRINTTS | [35-32] | y |
@@ -234,10 +242,18 @@ infrastructure:
+------------------------------+---------+---------+
| Name | bits | visible |
+------------------------------+---------+---------+
+ | F64MM | [59-56] | y |
+ +------------------------------+---------+---------+
+ | F32MM | [55-52] | y |
+ +------------------------------+---------+---------+
+ | I8MM | [47-44] | y |
+ +------------------------------+---------+---------+
| SM4 | [43-40] | y |
+------------------------------+---------+---------+
| SHA3 | [35-32] | y |
+------------------------------+---------+---------+
+ | BF16 | [23-20] | y |
+ +------------------------------+---------+---------+
| BitPerm | [19-16] | y |
+------------------------------+---------+---------+
| AES | [7-4] | y |
diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst
index 7fa3d215ae6a..7dfb97dfe416 100644
--- a/Documentation/arm64/elf_hwcaps.rst
+++ b/Documentation/arm64/elf_hwcaps.rst
@@ -204,6 +204,37 @@ HWCAP2_FRINT
Functionality implied by ID_AA64ISAR1_EL1.FRINTTS == 0b0001.
+HWCAP2_SVEI8MM
+
+ Functionality implied by ID_AA64ZFR0_EL1.I8MM == 0b0001.
+
+HWCAP2_SVEF32MM
+
+ Functionality implied by ID_AA64ZFR0_EL1.F32MM == 0b0001.
+
+HWCAP2_SVEF64MM
+
+ Functionality implied by ID_AA64ZFR0_EL1.F64MM == 0b0001.
+
+HWCAP2_SVEBF16
+
+ Functionality implied by ID_AA64ZFR0_EL1.BF16 == 0b0001.
+
+HWCAP2_I8MM
+
+ Functionality implied by ID_AA64ISAR1_EL1.I8MM == 0b0001.
+
+HWCAP2_BF16
+
+ Functionality implied by ID_AA64ISAR1_EL1.BF16 == 0b0001.
+
+HWCAP2_DGH
+
+ Functionality implied by ID_AA64ISAR1_EL1.DGH == 0b0001.
+
+HWCAP2_RNG
+
+ Functionality implied by ID_AA64ISAR0_EL1.RNDR == 0b0001.
4. Unused AT_HWCAP bits
-----------------------
diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 99b2545455ff..9120e59578dc 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -88,6 +88,8 @@ stable kernels.
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Cortex-A76 | #1463225 | ARM64_ERRATUM_1463225 |
+----------------+-----------------+-----------------+-----------------------------+
+| ARM | Cortex-A55 | #1530923 | ARM64_ERRATUM_1530923 |
++----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 |
+----------------+-----------------+-----------------+-----------------------------+
| ARM | Neoverse-N1 | #1349291 | N/A |
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst
index fcedc5349ace..640934b6f7b4 100644
--- a/Documentation/core-api/xarray.rst
+++ b/Documentation/core-api/xarray.rst
@@ -25,10 +25,6 @@ good performance with large indices. If your index can be larger than
``ULONG_MAX`` then the XArray is not the data type for you. The most
important user of the XArray is the page cache.
-Each non-``NULL`` entry in the array has three bits associated with
-it called marks. Each mark may be set or cleared independently of
-the others. You can iterate over entries which are marked.
-
Normal pointers may be stored in the XArray directly. They must be 4-byte
aligned, which is true for any pointer returned from kmalloc() and
alloc_page(). It isn't true for arbitrary user-space pointers,
@@ -41,12 +37,11 @@ When you retrieve an entry from the XArray, you can check whether it is
a value entry by calling xa_is_value(), and convert it back to
an integer by calling xa_to_value().
-Some users want to store tagged pointers instead of using the marks
-described above. They can call xa_tag_pointer() to create an
-entry with a tag, xa_untag_pointer() to turn a tagged entry
-back into an untagged pointer and xa_pointer_tag() to retrieve
-the tag of an entry. Tagged pointers use the same bits that are used
-to distinguish value entries from normal pointers, so each user must
+Some users want to tag the pointers they store in the XArray. You can
+call xa_tag_pointer() to create an entry with a tag, xa_untag_pointer()
+to turn a tagged entry back into an untagged pointer and xa_pointer_tag()
+to retrieve the tag of an entry. Tagged pointers use the same bits that
+are used to distinguish value entries from normal pointers, so you must
decide whether they want to store value entries or tagged pointers in
any particular XArray.
@@ -56,10 +51,9 @@ conflict with value entries or internal entries.
An unusual feature of the XArray is the ability to create entries which
occupy a range of indices. Once stored to, looking up any index in
the range will return the same entry as looking up any other index in
-the range. Setting a mark on one index will set it on all of them.
-Storing to any index will store to all of them. Multi-index entries can
-be explicitly split into smaller entries, or storing ``NULL`` into any
-entry will cause the XArray to forget about the range.
+the range. Storing to any index will store to all of them. Multi-index
+entries can be explicitly split into smaller entries, or storing ``NULL``
+into any entry will cause the XArray to forget about the range.
Normal API
==========
@@ -87,17 +81,11 @@ If you want to only store a new entry to an index if the current entry
at that index is ``NULL``, you can use xa_insert() which
returns ``-EBUSY`` if the entry is not empty.
-You can enquire whether a mark is set on an entry by using
-xa_get_mark(). If the entry is not ``NULL``, you can set a mark
-on it by using xa_set_mark() and remove the mark from an entry by
-calling xa_clear_mark(). You can ask whether any entry in the
-XArray has a particular mark set by calling xa_marked().
-
You can copy entries out of the XArray into a plain array by calling
-xa_extract(). Or you can iterate over the present entries in
-the XArray by calling xa_for_each(). You may prefer to use
-xa_find() or xa_find_after() to move to the next present
-entry in the XArray.
+xa_extract(). Or you can iterate over the present entries in the XArray
+by calling xa_for_each(), xa_for_each_start() or xa_for_each_range().
+You may prefer to use xa_find() or xa_find_after() to move to the next
+present entry in the XArray.
Calling xa_store_range() stores the same entry in a range
of indices. If you do this, some of the other operations will behave
@@ -124,6 +112,31 @@ xa_destroy(). If the XArray entries are pointers, you may wish
to free the entries first. You can do this by iterating over all present
entries in the XArray using the xa_for_each() iterator.
+Search Marks
+------------
+
+Each entry in the array has three bits associated with it called marks.
+Each mark may be set or cleared independently of the others. You can
+iterate over marked entries by using the xa_for_each_marked() iterator.
+
+You can enquire whether a mark is set on an entry by using
+xa_get_mark(). If the entry is not ``NULL``, you can set a mark on it
+by using xa_set_mark() and remove the mark from an entry by calling
+xa_clear_mark(). You can ask whether any entry in the XArray has a
+particular mark set by calling xa_marked(). Erasing an entry from the
+XArray causes all marks associated with that entry to be cleared.
+
+Setting or clearing a mark on any index of a multi-index entry will
+affect all indices covered by that entry. Querying the mark on any
+index will return the same result.
+
+There is no way to iterate over entries which are not marked; the data
+structure does not allow this to be implemented efficiently. There are
+not currently iterators to search for logical combinations of bits (eg
+iterate over all entries which have both ``XA_MARK_1`` and ``XA_MARK_2``
+set, or iterate over all entries which have ``XA_MARK_0`` or ``XA_MARK_2``
+set). It would be possible to add these if a user arises.
+
Allocating XArrays
------------------
@@ -180,6 +193,8 @@ No lock needed:
Takes RCU read lock:
* xa_load()
* xa_for_each()
+ * xa_for_each_start()
+ * xa_for_each_range()
* xa_find()
* xa_find_after()
* xa_extract()
@@ -419,10 +434,9 @@ you last processed. If you have interrupts disabled while iterating,
then it is good manners to pause the iteration and reenable interrupts
every ``XA_CHECK_SCHED`` entries.
-The xas_get_mark(), xas_set_mark() and
-xas_clear_mark() functions require the xa_state cursor to have
-been moved to the appropriate location in the xarray; they will do
-nothing if you have called xas_pause() or xas_set()
+The xas_get_mark(), xas_set_mark() and xas_clear_mark() functions require
+the xa_state cursor to have been moved to the appropriate location in the
+XArray; they will do nothing if you have called xas_pause() or xas_set()
immediately before.
You can call xas_set_update() to have a callback function
diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst
index 36890b026e77..1c4e1825d769 100644
--- a/Documentation/dev-tools/kcov.rst
+++ b/Documentation/dev-tools/kcov.rst
@@ -251,11 +251,11 @@ selectively from different subsystems.
.. code-block:: c
struct kcov_remote_arg {
- unsigned trace_mode;
- unsigned area_size;
- unsigned num_handles;
- uint64_t common_handle;
- uint64_t handles[0];
+ __u32 trace_mode;
+ __u32 area_size;
+ __u32 num_handles;
+ __aligned_u64 common_handle;
+ __aligned_u64 handles[0];
};
#define KCOV_INIT_TRACE _IOR('c', 1, unsigned long)
diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst
index 9d6db892c41c..4e1d24db6b13 100644
--- a/Documentation/dev-tools/kunit/start.rst
+++ b/Documentation/dev-tools/kunit/start.rst
@@ -24,19 +24,16 @@ The wrapper can be run with:
For more information on this wrapper (also called kunit_tool) checkout the
:doc:`kunit-tool` page.
-Creating a kunitconfig
-======================
+Creating a .kunitconfig
+=======================
The Python script is a thin wrapper around Kbuild. As such, it needs to be
-configured with a ``kunitconfig`` file. This file essentially contains the
+configured with a ``.kunitconfig`` file. This file essentially contains the
regular Kernel config, with the specific test targets as well.
.. code-block:: bash
- git clone -b master https://kunit.googlesource.com/kunitconfig $PATH_TO_KUNITCONFIG_REPO
cd $PATH_TO_LINUX_REPO
- ln -s $PATH_TO_KUNIT_CONFIG_REPO/kunitconfig kunitconfig
-
-You may want to add kunitconfig to your local gitignore.
+ cp arch/um/configs/kunit_defconfig .kunitconfig
Verifying KUnit Works
---------------------
@@ -151,7 +148,7 @@ and the following to ``drivers/misc/Makefile``:
obj-$(CONFIG_MISC_EXAMPLE_TEST) += example-test.o
-Now add it to your ``kunitconfig``:
+Now add it to your ``.kunitconfig``:
.. code-block:: none
diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
index 2210f4359c45..8347b1e7c080 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-at91.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
@@ -18,8 +18,10 @@ Optional properties:
- dma-names: should contain "tx" and "rx".
- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO
capable I2C controllers.
-- i2c-sda-hold-time-ns: TWD hold time, only available for "atmel,sama5d4-i2c"
- and "atmel,sama5d2-i2c".
+- i2c-sda-hold-time-ns: TWD hold time, only available for:
+ "atmel,sama5d4-i2c",
+ "atmel,sama5d2-i2c",
+ "microchip,sam9x60-i2c".
- Child nodes conforming to i2c bus binding
Examples :
diff --git a/Documentation/devicetree/bindings/net/fsl-fman.txt b/Documentation/devicetree/bindings/net/fsl-fman.txt
index 299c0dcd67db..250f8d8cdce4 100644
--- a/Documentation/devicetree/bindings/net/fsl-fman.txt
+++ b/Documentation/devicetree/bindings/net/fsl-fman.txt
@@ -403,6 +403,19 @@ PROPERTIES
The settings and programming routines for internal/external
MDIO are different. Must be included for internal MDIO.
+- fsl,erratum-a011043
+ Usage: optional
+ Value type: <boolean>
+ Definition: Indicates the presence of the A011043 erratum
+ describing that the MDIO_CFG[MDIO_RD_ER] bit may be falsely
+ set when reading internal PCS registers. MDIO reads to
+ internal PCS registers may result in having the
+ MDIO_CFG[MDIO_RD_ER] bit set, even when there is no error and
+ read data (MDIO_DATA[MDIO_DATA]) is correct.
+ Software may get false read error when reading internal
+ PCS registers through MDIO. As a workaround, all internal
+ MDIO accesses should ignore the MDIO_CFG[MDIO_RD_ER] bit.
+
For internal PHY device on internal mdio bus, a PHY node should be created.
See the definition of the PHY node in booting-without-of.txt for an
example of how to define a PHY (Internal PHY has no interrupt line).
diff --git a/Documentation/devicetree/bindings/spi/spi-controller.yaml b/Documentation/devicetree/bindings/spi/spi-controller.yaml
index 732339275848..1e0ca6ccf64b 100644
--- a/Documentation/devicetree/bindings/spi/spi-controller.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-controller.yaml
@@ -111,7 +111,7 @@ patternProperties:
spi-rx-bus-width:
allOf:
- $ref: /schemas/types.yaml#/definitions/uint32
- - enum: [ 1, 2, 4 ]
+ - enum: [ 1, 2, 4, 8 ]
- default: 1
description:
Bus width to the SPI bus used for MISO.
@@ -123,7 +123,7 @@ patternProperties:
spi-tx-bus-width:
allOf:
- $ref: /schemas/types.yaml#/definitions/uint32
- - enum: [ 1, 2, 4 ]
+ - enum: [ 1, 2, 4, 8 ]
- default: 1
description:
Bus width to the SPI bus used for MOSI.
diff --git a/Documentation/features/debug/gcov-profile-all/arch-support.txt b/Documentation/features/debug/gcov-profile-all/arch-support.txt
index 059d58a549c7..6fb2b0671994 100644
--- a/Documentation/features/debug/gcov-profile-all/arch-support.txt
+++ b/Documentation/features/debug/gcov-profile-all/arch-support.txt
@@ -23,7 +23,7 @@
| openrisc: | TODO |
| parisc: | TODO |
| powerpc: | ok |
- | riscv: | TODO |
+ | riscv: | ok |
| s390: | ok |
| sh: | ok |
| sparc: | TODO |
diff --git a/Documentation/media/v4l-drivers/meye.rst b/Documentation/media/v4l-drivers/meye.rst
index a572996cdbf6..dc57a6a91b43 100644
--- a/Documentation/media/v4l-drivers/meye.rst
+++ b/Documentation/media/v4l-drivers/meye.rst
@@ -95,7 +95,7 @@ so all video4linux tools (like xawtv) should work with this driver.
Besides the video4linux interface, the driver has a private interface
for accessing the Motion Eye extended parameters (camera sharpness,
-agc, video framerate), the shapshot and the MJPEG capture facilities.
+agc, video framerate), the snapshot and the MJPEG capture facilities.
This interface consists of several ioctls (prototypes and structures
can be found in include/linux/meye.h):
diff --git a/Documentation/networking/dsa/sja1105.rst b/Documentation/networking/dsa/sja1105.rst
index eef20d0bcf7c..64553d8d91cb 100644
--- a/Documentation/networking/dsa/sja1105.rst
+++ b/Documentation/networking/dsa/sja1105.rst
@@ -230,12 +230,6 @@ simultaneously on two ports. The driver checks the consistency of the schedules
against this restriction and errors out when appropriate. Schedule analysis is
needed to avoid this, which is outside the scope of the document.
-At the moment, the time-aware scheduler can only be triggered based on a
-standalone clock and not based on PTP time. This means the base-time argument
-from tc-taprio is ignored and the schedule starts right away. It also means it
-is more difficult to phase-align the scheduler with the other devices in the
-network.
-
Device Tree bindings and board design
=====================================
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index fd26788e8c96..48ccb1b31160 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -603,7 +603,7 @@ tcp_synack_retries - INTEGER
with the current initial RTO of 1second. With this the final timeout
for a passive TCP connection will happen after 63seconds.
-tcp_syncookies - BOOLEAN
+tcp_syncookies - INTEGER
Only valid when the kernel was compiled with CONFIG_SYN_COOKIES
Send out syncookies when the syn backlog queue of a socket
overflows. This is to prevent against the common 'SYN flood attack'
diff --git a/Documentation/networking/netdev-FAQ.rst b/Documentation/networking/netdev-FAQ.rst
index 642fa963be3c..d5c9320901c3 100644
--- a/Documentation/networking/netdev-FAQ.rst
+++ b/Documentation/networking/netdev-FAQ.rst
@@ -34,8 +34,8 @@ the names, the ``net`` tree is for fixes to existing code already in the
mainline tree from Linus, and ``net-next`` is where the new code goes
for the future release. You can find the trees here:
-- https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git
-- https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
+- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
+- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
Q: How often do changes from these trees make it to the mainline Linus tree?
----------------------------------------------------------------------------
diff --git a/Documentation/process/embargoed-hardware-issues.rst b/Documentation/process/embargoed-hardware-issues.rst
index 799580acc8de..5d54946cfc75 100644
--- a/Documentation/process/embargoed-hardware-issues.rst
+++ b/Documentation/process/embargoed-hardware-issues.rst
@@ -255,7 +255,7 @@ an involved disclosed party. The current ambassadors list:
Red Hat Josh Poimboeuf <jpoimboe@redhat.com>
SUSE Jiri Kosina <jkosina@suse.cz>
- Amazon
+ Amazon Peter Bowen <pzb@amzn.com>
Google Kees Cook <keescook@chromium.org>
============= ========================================================
diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst
index 21aa7d5358e6..6399d92f0b21 100644
--- a/Documentation/process/index.rst
+++ b/Documentation/process/index.rst
@@ -60,6 +60,7 @@ lack of a better place.
volatile-considered-harmful
botching-up-ioctls
clang-format
+ ../riscv/patch-acceptance
.. only:: subproject and html
diff --git a/Documentation/riscv/index.rst b/Documentation/riscv/index.rst
index 215fd3c1f2d5..fa33bffd8992 100644
--- a/Documentation/riscv/index.rst
+++ b/Documentation/riscv/index.rst
@@ -7,6 +7,7 @@ RISC-V architecture
boot-image-header
pmu
+ patch-acceptance
.. only:: subproject and html
diff --git a/Documentation/riscv/patch-acceptance.rst b/Documentation/riscv/patch-acceptance.rst
new file mode 100644
index 000000000000..dfe0ac5624fb
--- /dev/null
+++ b/Documentation/riscv/patch-acceptance.rst
@@ -0,0 +1,35 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+arch/riscv maintenance guidelines for developers
+================================================
+
+Overview
+--------
+The RISC-V instruction set architecture is developed in the open:
+in-progress drafts are available for all to review and to experiment
+with implementations. New module or extension drafts can change
+during the development process - sometimes in ways that are
+incompatible with previous drafts. This flexibility can present a
+challenge for RISC-V Linux maintenance. Linux maintainers disapprove
+of churn, and the Linux development process prefers well-reviewed and
+tested code over experimental code. We wish to extend these same
+principles to the RISC-V-related code that will be accepted for
+inclusion in the kernel.
+
+Submit Checklist Addendum
+-------------------------
+We'll only accept patches for new modules or extensions if the
+specifications for those modules or extensions are listed as being
+"Frozen" or "Ratified" by the RISC-V Foundation. (Developers may, of
+course, maintain their own Linux kernel trees that contain code for
+any draft extensions that they wish.)
+
+Additionally, the RISC-V specification allows implementors to create
+their own custom extensions. These custom extensions aren't required
+to go through any review or ratification process by the RISC-V
+Foundation. To avoid the maintenance complexity and potential
+performance impact of adding kernel code for implementor-specific
+RISC-V extensions, we'll only to accept patches for extensions that
+have been officially frozen or ratified by the RISC-V Foundation.
+(Implementors, may, of course, maintain their own Linux kernel trees
+containing code for any custom extensions that they wish.)