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Posts Tagged ‘ubifs’

Linux 4.0 Release – Main Changes, ARM and MIPS Architectures

April 15th, 2015 6 comments

Linus Torvalds “Ima Sheep” released Linux Kernel 4.0 on Sunday:

So I decided to release 4.0 as per the normal schedule, because there really weren’t any known issues, and while I’ll be traveling during the end of the upcoming week due to a college visit, I’m hoping that won’t affect the merge window very much. We’ll see.

Linux 4.0 was a pretty small release both in linux-next and in final size, although obviously “small” is all relative. It’s still over 10k non-merge commits. But we’ve definitely had bigger releases (and judging by linux-next v4.1 is going to be one of the bigger ones).

Which is all good. It definitely matches the “v4.0 is supposed to be a_stable_ release”, and very much not about new experimental features etc. I’m personally so much happier with time-based releases than the bad old days when we had feature-based releases.

That said, there’s a few interesting numerological things going on with 4.0. Looking at just the statistics in git, this release is not just when we cross half a million commits total, but also cross the 4 million git object limit. Interestingly (if you look for numeric patterns), Linux 3.0 was when we crossed a quarter million commits and 2 million git objects, so there’s a nice (and completely unintentional) pattern there when it comes to the kernel git repository.

[ Another quick historical numerological footnote: the old historical BK tree was getting close to the 16-bit commilt limit that BK originally used to have. So that whole “quarter of a million commits” is actually quite a lot. During all of the BK years we only got 65k commits. Of course, we only used BK for three years, and we’ve now been on git for almost exactly ten years, but still – it shows how the whole development process has really sped up a _lot_ ]

Feature-wise, 4.0 doesn’t have all that much special. Much have been made of the new kernel patching infrastructure, but realistically, that not only wasn’t the reason for the version number change, we’ve had much bigger changes in other versions. So this is very much a “solid code progress” release.

Go get it and enjoy,

Linus “we’re all sheep” Torvalds

Linux 3.19 brought improvement to btrfs (raid), the network stack, added ARM Coresight, device tree overlays support, and more.

Some key changes made to Linux 4.0 include:

  • pNFS (Parallel NFS), UBIFS, F2FS and BTRFS File Systems improvements
  • Live Kernel Patching – Install kernel updates without rebooting
  • Intel Quark x86 SoC support
  • Various patches to improve Linux running on a  Playstation 3
  • Open source AMD Radeon driver supports DisplayPort Audio and improves fan support

Some of the new features and improvements specific to the ARM architecture include:

  • Allwinner:
    • A20 – PS/2 Controller
    • A31 – IR receiver
    • A31s – Bring-up sharing majority of drivers with A31, pinctrl driver
    • A80 – MMC
    • All SoCs – LRADC Input driver, CPUFreq, PWM Driver
    • AXP209 power button input driver
    • New boards and devices:  CSQ CS908, LeMaker Banana Pro, Chuwi V7 CW0825, Rikomagic mk802, Rikomagic mk802ii, Rikomagic mk802_a10s, MarsBoard A10, Hyundai A7HD
  • Rockchip
    • Fixes for rk808 regulator
    • Watchdog fix
    • Add Rockchip timer for RK3288
    • HDMI output enabled on rk3288-firefly and rk3288-evb
    • Disable GMAC by default
  • Amlogic – pinctrl driver for Amlogic Meson SoCs
  • Mediatek
    • Regulator driver for Mediatek MT6397
    • Added watchdog driver
    • Added Mediatek MT8173 64-bit processor
  • ARM64
    • New processors: Exynos 7, Freescale LS2085A, and Tegra 132 (Denver)
    • Various fixes for ARM64 including UEFI and KVM code.
  • Preparation work for Atmel AT91 support for multiplatform
  • Other new platforms – Alphascale ASM9260, Marvell Armada 388, CSR Atlas7, TI Davinci DM816x, Hisilicon HiP01, ST STiH418, and Conexant Digicolor (CX92755).

There has also been some interesting changes for the MIPS architecture:

  • Fixes for KVM support
  • Support for MIPS R6 processors
  • Preliminary support for Cavium Octeon 3 SoCs which feature up to 48 MIPS64 R3 cores with FPU and hardware virtualization

A more detailed changelog for Linux 4.0 will soon be available on Kernelnewbies.org, and once it’s up you may also want to have a look at their ARM architecture and drivers sections for more details about changes related to ARM, MIPS and other platforms. I’ve also generated a complete Linux 3.19 vs Linux 4.0 changelog (3.4MB) with git (comments only, no code).

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UBI Fastmap – ELCE 2012

January 17th, 2013 No comments

Thomas Gleixner, Linux kernel programmer at Linutronix, talks about UBI flash management layer, and fastmap implementation to speed up boot times at the Embedded Linux Conference Europe, on November 7, 2012.

Abstract:

UBI is a flash management layer in the Linux kernel designed to handle especially the shortcomings of NAND flash. UBI itself has the requirement to scan the full flash at boot time. With flash sizes becoming larger and larger this can take quite some time. A recent development implemented fast mapping functionality which is designed to put an upper bound on the number of flash eraseblocks to scan. This allows faster boot times without sacrifying the robustness of UBI. This talk gives an overview of the UBI fastmap design and looks at costs and benefits.

UBIFS

The talk provides an overview of UBI and its shortcomings, and explains UBI fastmap implementation in details showing it provides significant speedup proportional to the flash size. UBI fastmap has been merged in Kernel 3.7.

You can also download the presentation slides for this talk.

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Status of Embedded Linux – ELC 2012

February 26th, 2012 No comments

Tim Bird, software engineer at Sony, discusses recent development in embedded Linux at the Embedded Linux Conference 2012.

Abstract:  Tim discusses changes to the kernel, improvements to embedded-related sub-systems, and new industry initiatives likely to affect embedded Linux developers in the future. Also, Tim discusses the direction of the Linux Foundation CE Workgroup, and their contract work and projects for this year. Last year highlights are also discussed, as well as ways to continue to improve Linux going forward.

Here are the key points of this presentation:

  • Linux Kernel Version changes: 2.6.38 to 3.3-rc3
  • Technology Areas:
    • Bootup Time  – With improvement in the kernel, bootloader and user-space
    • Graphics – 2D/3D implementation. New /dev/ion and CMA graphics stuffs
    • Accelerated Rendering – e.g. Renderscript
    • Graphics Drivers – e.g. PowerVR
    • Multimedia – Gstreamer, Android Media Layer (stagefright) and codec wars (e.g. patent issues with WebM/VP8 that interferes open source licenses).
    • File systems – Mainly UBIFS (default raw flash file system replacing JFFS2) and YAFFS2. But Google is moving to ext-4 with eMMC devices.
    • Power Management
    • System Size – Work is still going on on low footprint distros such as linux-tiny and poky-tiny.

    The hot areas right now are power management, ARM board support refactoring and GPU management.

  • CE Workgroup Projects:
  • Miscellaneous:
    • Tools:
      • Qemu for Linux and Android emulation
      • Eclipse
      • Tracing tools (Perf, ftrace, LTTng 2.0)
    • Build Systems: Yocto project and custom build systems.
    • Embedded Distributions:
      • Tizen
      • WebOS
      • Legacy Custom embedded distros (no standard)
    • Android 4.0 SDK release (last October)
    • Resources:
      • Stack Overflow is used more and more for embedded Linux
      • elinux.org Wiki has got a lot of good documentation
      • LWN.net to follow kernel changes.

You can also download the presentation slides on elinux.org.

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