Linux 4.13 Release - Main Changes, ARM & MIPS Architectures

Linus Torvalds has just announced the release of Linux 4.13 and a kidney stone…:

So last week was actually somewhat eventful, but not enough to push me to delay 4.13.

Most of the changes since rc7 are actually networking fixes, the bulk of them to various drivers. With apologies to the authors of said patches, they don’t look all that interesting (which is definitely exactly what you want just before a release). Details in the appended shortlog.

Note that the shortlog below is obviously only since rc7 – the _full_4.13 log is much too big to post and nobody sane would read it. So if you’re interested in all the rest of it, get the git tree and limit the logs to the files you are interested in if you crave details.

No, the excitement was largely in the mmu notification layer, where we had a fairly last-minute regression and some discussion about the problem. Lots of kudos to Jérôme Glisse for jumping on it, and implementing the fix.

What’s nice to see is that the regression pointed out a nasty and not very well documented (or thought out) part of the mmu notifiers, and the fix not only fixed the problem, but did so by cleaning up and documenting what the right behavior should be, and furthermore did so by getting rid of the problematic notifier and actually removing almost two hundred lines in the process.

I love seeing those kinds of fixes. Better, smaller, code.

The other excitement this week was purely personal, consisting of seven hours of pure agony due to a kidney stone. I’m all good, but it sure _felt_ a lot longer than seven hours, and I don’t even want to imagine what it is for people that have had the experience drag out for longer. Ugh.

Anyway, on to actual 4.13 issues.

While we’ve had lots of changes all over (4.13 was not particularly big, but even a “solidly average” release is not exactly small), one very _small_ change merits some extra attention, because it’s one of those very rare changes where we change behavior due to security issues, and where people may need to be aware of that behavior change when upgrading.

This time it’s not really a kernel security issue, but a generic protocol security issue.

The change in question is simply changing the default cifs behavior: instead of defaulting to SMB 1.0 (which you really should not use: just google for “stop using SMB1” or similar), the default cifs mount now defaults to a rather more modern SMB 3.0.

Now, because you shouldn’t have been using SMB1 anyway, this shouldn’t affect anybody. But guess what? It almost certainly does affect some people, because they blithely continued using SMB1 without really thinking about it.

And you certainly _can_ continue to use SMB1, but due to the default change, now you need to be *aware* of it. You may need to add an explicit “vers=1.0” to your mount options in /etc/fstab or similar if you *really* want SMB1.

But if the new default of 3.0 doesn’t work (because you still use a pterodactyl as a windshield wiper), before you go all the way back to the bad old days and use that “vers=1.0”, you might want to try “vers=2.1”. Because let’s face it, SMB1 is just bad, bad, bad.

Anyway, most people won’t notice at all. And the ones that do notice can check their current situation (just look at the output of “mount” and see if you have any cifs things there), and you really should update from the default even if you are *not* upgrading kernels.

Ok, enough about that. It was literally a two-liner change top defaults – out of the million or so lines of the full 4.13 patch changing real code.

Go get the new kernel,

Linus

Two months ago, Linux 4.12 was released with initial support for AMD Radeon RX Vega GPU, BFQ (Budget Fair Queuing) and Kyber block I/O schedulers, AnalyzeBoot tool for the kernel, “hybrid consistency model” implementation for live kernel patching, but disabled the Open Sound System, and removed AVR32 support, among many other changes.

Some interesting changes in Linux 4.13 – mostly based on LWN 4.13 Merge Window part 1 & part 2 – include:

Support for non-blocking buffered I/O operations added at the block level, which should also improve asynchronous I/O support when used with buffered I/O.
AppArmor security module’s “domain labeling” code has been merged into the mainline. It was maintained by Ubuntu out of tree previously.
Kernel-based TLS implementation that should deliver better performance for HTTPS, and other protocol relying on TLS.
CIFS/SAMBA now defaults to v3.0 instead of v1.0 due to security issues
File System Changes – EXT-4: support for to ~2 billion files per directory with largedir option, extended attributes up to 64KB, new deduplication feature; f2fs: supports disk quotas; overlayfs union: new “index directory” feature that makes copy-up operations work without breaking hard links.

Changes specific to ARM include:

Allwinner:
- Allwinner A10s – HDMI support
- Allwinner V3s – Clock driver & DRM/KMS display driver for Display Engine 2.0; Audio codec support
- Allwinner A83T – Clock driver
- DTS Changes:
  - SoC specific – LRADC, MMC1, SPI, Display Engine 2.0 for V3s
  - Board specific
    - Enabled AXP PMIC battery support on NextThingCo CHIP, Sinlinx SinA33
    - Enable USB OTG on Banana Pi M2+, Orange Pi PC, Orange Pi PC Plus, Orange Pi Plus 2E
    - Enable dedicated USB hosts for USB OTG on Pine64
- Added support for: NanoPi NEO2, Orange Pi Prime, Lichee Pi Zero dock board, Orange Pi Zero Plus 2, SoPine SoM, NanoPi M1 Plus

Rockchip:
- Added support for RV1108 SoC for camera applications
- Rockchip IOMMU driver is now available on ARM64
- PCIe – configure Rockchip MPS and reorganize + use normal register bank
- Clock driver for Rockchip RK3128 SoC
- Rockchip pinctrl driver now supports iomux-route switching for RK3228, RK3328 and RK3399
- Sound driver – Support for Rockchip PDM controllers
- Device tree
  - Added RK3399-Firefly SBC
  - Added ARM Mali GPU
  - Added cru
  - Added sdmmc, sdio, emmc nodes for Rockchip RK3328

Amlogic
- Updated CEC EE clock support
- Enabled clock controller for 32-bit Meson8
- Device tree changes
  - Meson UARTs
  - new SPI controller driver
  - HDMI & CVBS for multiple boards
  - new pinctrl pins for SPI, HDMI CEC, PWM
  - Ethernet Link and Activity LEDs pin nodes
  - SAR ADC support for Meson8 & Meson8b
- Defconfig changes – Meson SPICC enabled as module; IR core, decoders and Meson IR device enabled;
- New boards & devices: NanoPi K2, Libre Computer SBC, R-Box Pro
Samsung
- Clock driver updated for Samsung Exynos 5420 audio clocks, and converted code to clk_hw registration APIs
- Pinctrl drivers split per ARMv7 and ARMv8 since there’s no need to compile everything on each of them
- ARM DT updates:
  - Add HDMI CEC to Exynos5 SoCs + needed property for CEC on Odroid U3
  - Fix reset GPIO polarity on Rinato
  - Minor cleanups and readability improvements.
- ARM64 DT updates:
  - Remove unneeded TE interrupt gpio property
- Defconfig changes – Some cleanups, enabled Exynos PRNG along with user-space crypto API.
Qualcomm
- Clock & pinctrl drivers for Qualcomm IPQ8074
- Add debug UART addresses for IPQ4019
- Improve QCOM SMSM error handling
- Defconfig
  - Enable HWSPINLOCK & RPMSG_QCOM_SMD to get some Qualcomm boards to work out of the box/again
  - Enable IPQ4019 clock and pinctrl
- Mailbox – New controller driver for Qualcomm’s APCS IPC
- RPMsg – Qualcomm GLINK protocol driver and DeviceTree-based modalias support, as well as a number of smaller fixes
- Qualcomm Device Tree Changes
  - Fix IPQ4019 i2c0 node
  - Add GSBI7 on IPQ8064
  - Add misc APQ8060 devices
  - Fixup USB related devices on APQ8064 and MSM8974
- Qualcomm ARM64 Updates for v4.12
  - Fix APQ8016 SBC WLAN LED
  - Add MSM8996 CPU node
  - Add MSM8992 SMEM and fixed regulator
  - Fixup MSM8916 USB support
Mediatek
- CPU clks for Mediatek MT8173/MT2701/MT7623 SoCs
- Pinctrl – Serious code size cut for MT7623
- Mediatek “scpsys” system controller support for MT6797
- Device tree
  - Added support for MT6797 (Helio X20) mobile SoC and evaluation board
  - Extended MT7623 support significantly
  - Added MT2701 i2c device & JPEG decoder nodes
Other new ARM hardware platforms and SoCs:
- STM32 – stm32h743-disco, stm32f746-disco, and stm32f769-disco boards; Drivers for digital audio interfaces, S/PDIF receiver, digital camera interfaces, HDMI CEC, watchdog timer
- NXP – Gateworks Ventana GW5600 SBC; Technexion Pico i.MX7D board; i.MX5/6 image processing units & camera sensor interfaces
- Realtek – Initial support for Realtek RTD1295 SoC and Zidoo X9S set-top-box
- Actions Semi – Initial support for Actions Semi S900 / S500, and corresponding LeMaker Guitar & Bubblegum-96 SBCs
- Renesas – Salvator-XS and H3ULCB automotive development systems; GR-Peach board, iWave G20D-Q7 System-on-Module plus
- Socionext- Support for Uniphier board support for LD11-global and LD20-global
- Broadcom – Stingray communication processor and two reference boards;
- Marvell – Linksys WRT3200ACM router
- Texas Instruments – BeagleBone Blue
- Microchip / Atmel – MMU-less ARM Cortex-M7 SoCs (SAME70/V71/S70/V70)

Some of the changes specific to MIPS include:

Boston platform support – Document DT bindings; Add CLK driver for board clocks
CM – Avoid per-core locking with CM3 & higher; WARN on attempt to lock invalid VP, not BUG
CPS – Select CONFIG_SYS_SUPPORTS_SCHED_SMT for MIPSr6; Prevent multi-core with dcache aliasing; Handle cores not powering down more gracefully; Handle spurious VP starts more gracefully
DSP – Add lwx & lhx missaligned access support
eBPF – Add MIPS support along with many supporting change to add the required infrastructure
Generic arch code:
- Misc sysmips MIPS_ATOMIC_SET fixes
- Drop duplicate HAVE_SYSCALL_TRACEPOINTS
- Negate error syscall return in trace
- Correct forced syscall errors
- Traced negative syscalls should return -ENOSYS
- Allow samples/bpf/tracex5 to access syscall arguments for sane
  traces
- Cleanup from old Kconfig options in defconfigs
- Fix PREF instruction usage by memcpy for MIPS R6
- Fix various special cases in the FPU eulation
- Fix some special cases in MIPS16e2 support
- Fix MIPS I ISA /proc/cpuinfo reporting
- Sort MIPS Kconfig alphabetically
- Fix minimum alignment requirement of IRQ stack as required by ABI / GCC
- Fix special cases in the module loader
- Perform post-DMA cache flushes on systems with MAARs
- Probe the I6500 CPU
- Cleanup cmpxchg and add support for 1 and 2 byte operations
- Use queued read/write locks (qrwlock)
- Use queued spinlocks (qspinlock)
- Add CPU shared FTLB feature detection
- Handle tlbex-tlbp race condition
- Allow storing pgd in C0_CONTEXT for MIPSr6
- Use current_cpu_type() in m4kc_tlbp_war()
- Support Boston in the generic kernel
Generic platform:
- yamon-dt: Pull YAMON DT shim code out of SEAD-3 board; Support > 256MB of RAM; Use serial* rather than uart* aliases
- Abstract FDT fixup application
- Set RTC_ALWAYS_BCD to 0
- Add a MAINTAINERS entry
core kernel – qspinlock.c: include linux/prefetch.h
Add support for Loongson 3
Perf – Add I6500 support
SEAD-3 – Remove GIC timer from DT; set interrupt-parent per-device, not at root node; fix GIC interrupt specifiers
SMP – Skip IPI setup if we only have a single CPU
VDSO – Make comment match reality; improvements to time code in VDSO”
Various fixes:
- compressed boot: Ignore a generated .c file
- VDSO: Fix a register clobber list
- DECstation: Fix an int-handler.S CPU_DADDI_WORKAROUNDS regression
- Octeon: Fix recent cleanups that cleaned away a bit too much thus breaking the arch side of the EDAC and USB drivers.
- uasm: Fix duplicate const in “const struct foo const bar[]” which GCC 7.1 no longer accepts.
- Fix race on setting and getting cpu_online_mask
- Fix preemption issue. To do so cleanly introduce macro to get the size of L3 cache line.
- Revert include cleanup that sometimes results in build error
- MicroMIPS uses bit 0 of the PC to indicate microMIPS mode. Make sure this bit is set for kernel entry as well.
- Prevent configuring the kernel for both microMIPS and MT. There are no such CPUs currently and thus the combination is unsupported and results in build errors.
- ralink: mt7620: Add missing header

You can read the full Linux 4.13 changelog – with comments only – generated using git log v4.12..v4.13 --stat for the full details, and eventually kernelnewsbies’s Linux 4.13 changelog will be updated with an extensive list of chances.

Jean-Luc Aufranc (CNXSoft)

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.