4.1 Merge window, part 1
Linus started merging changes for the 4.1 development cycle on
April 13; as of this writing, a total of 3,643 non-merge changesets
have been pulled into the mainline. In other words, things are just
getting started. Still, some interesting changes have found their way in,
though many of them will be of interest mainly to kernel developers.
Some of the more interesting, user-visible changes merged so far include:
- Basic support for live kernel patching has been added to the S/390
architecture. What has been removed from S/390, instead, is support
for the 31-bit mode,
once needed to get past that pesky 16MB memory limit.
- KVM virtualization on the MIPS architecture has gained support for the
floating-point unit and the SIMD mode. KVM on ARM now
supports interrupt injection via irqfd().
- Load tracking in the CPU scheduler has been reworked to make the
calculated process loads be independent of CPU speeds. That will enable
better load-balancing decisions in the presence of frequency scaling
and improve support for asymmetric systems like big.LITTLE where
different types of CPUs are found in the same package.
- New hardware support includes:
- I2C:
Digicolor I2C controllers,
Ingenic JZ4780 I2C controllers, and
Broadcom XLP9xx/XLP5xx I2C controllers.
- IIO:
Capella CM3323 color light sensors and
Measurement Specialties MS5611 pressure sensors.
- Input:
Broadcom keypad controllers,
MAXIM MAX77843 haptic controllers,
iPAQ h3100/h3600/h3700 buttons,
Semtech SX8654 I2C touchscreens,
Qualcomm PM8941 performance management IC (PMIC) power keys,
Broadcom IPROC touchscreens, and
ChipOne icn8318 I2C touchscreen controllers.
- Miscellaneous:
Nuvoton NCT7904 hardware-monitoring chips,
Broadcom IPROC SD/MMC and PCIe controllers,
Dialog DA9150 charger and fuel-gauge controllers,
X-Powers AXP288 fuel gauges,
Nokia modems implementing the CMT speech protocol,
Silicon Motion SM750 framebuffers,
Ilitek ILI9163 LCD controllers, and
Freescale Management Complex buses.
- Multi-function device:
Wolfson Microelectronics WM8280/WM8281 controllers,
MediaTek MT6397 PMICs,
Maxim Semiconductor MAX77843 PMICs,
Intel Quark controllers, and
Skyworks Solutions SKY81452 controllers.
- Pin control:
Marvell Armada 39x pin controllers,
NVIDIA Tegra210 pinmux controllers,
Broadcom Cygnus IOMUX controllers,
Mediatek mt8135 pin controllers,
AMD platform pin controllers, and
Intel Sunrisepoint pin controllers.
- USB: AltusMetrum ChaosKey random-number generators, TI dm816x USB PHYs, and Allwinner sun9i USB PHYs.
- I2C:
Digicolor I2C controllers,
Ingenic JZ4780 I2C controllers, and
Broadcom XLP9xx/XLP5xx I2C controllers.
Changes visible to kernel developers include:
- The kernel self-test code has gained an install target that
installs test binaries into a special directory in the kernel tree.
There is also a new set of timer self tests in the test suite.
- The new efi=debug boot option causes extra information to be
printed at boot time on systems with EFI firmware.
- The long-deprecated IRQF_DISABLED interrupt flag has finally
been removed from the kernel.
- The "tracefs" virtual filesystem has been added. Tracefs contains the
usual set of directories and files to control tracing, but it has the
advantage that it can be mounted independently of debugfs. It thus
allows system administrators to enable tracing without bringing in the
other, potentially dangerous knobs found in debugfs. By default,
tracefs will be mounted in the usual place
(/sys/kernel/debug/tracing) when debugfs is mounted.
- The new TRACE_DEFINE_ENUM() macro can be used to output
values from enum types in tracepoints.
- As usual, the perf tool has seen a long list of additions and
improvements; see the
top-level merge commit for details. Some of the more significant
features include the ability to attach BPF programs to kernel probes,
support for Intel's upcoming processor
trace functionality ("
a hardware tracer on steroids
"), support for Intel's upcoming cache quality-of-service monitoring feature, and more. - The I2C subsystem can now function in "slave" mode, responding to a master controller elsewhere on the bus; see Documentation/i2c/slave-interface for details. The I2C layer has also gained a new quirk mechanism that can be used to describe the limitations of specific controllers.
Unless something surprising happens, the merge window can be expected to
stay open through April 27. There will likely be a lull in the middle
while Linus travels, but that has tended to not slow things down too much
in the past. As usual, we will continue to track and report on the
significant changes merged for the 4.1 development cycle.
| Index entries for this article | |
|---|---|
| Kernel | Releases/4.1 |