Linux Wireless Drivers Freedom considered harmful? Felix Fietkau - - PowerPoint PPT Presentation

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Linux Wireless Drivers Freedom considered harmful? Felix Fietkau - - PowerPoint PPT Presentation

Linux Wireless Drivers Freedom considered harmful? Felix Fietkau <nbd@openwrt.org> 2015-12-30 Introduction OpenWrt developer for >10 years Involved with Linux wireless drivers almost as long Main focus: access points and


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Linux Wireless Drivers

Freedom considered harmful?

Felix Fietkau <nbd@openwrt.org> 2015-12-30

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Introduction

  • OpenWrt developer for >10 years
  • Involved with Linux wireless drivers almost as long
  • Main focus: access points and mesh nodes
  • Preference for widely available consumer devices

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Why do we need free 802.11 drivers?

  • Security
  • Stability
  • Maintenance costs / complexity
  • Interesting research projects
  • Features not deemed relevant by vendors

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My journey through Linux Wireless

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Early days: Broadcom BCM47xx

  • Binary-only driver for Linux 2.4
  • Kernel hacks to deal with ABI changes
  • Later partially replaced by b43

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Early days: MadWiFi

  • More ’free’ than the Broadcom blob
  • Still non-free binary parts
  • No kernel dependent binaries anymore

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ath5k

  • Finally a free replacement for MadWiFi
  • Based on reverse engineering
  • Useful prototype for developing mac80211 features

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ath9k

  • Developed by Atheros
  • Initial development driven by Laptop customer demand
  • Strong push from community people to open more code / documentation
  • Actually became stable enough for commercial use
  • Used by some embedded hardware vendors

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ath9k - Issues with Atheros (later QCA)

  • Progress often prevented by high turnover
  • Constant need to justify the development cost
  • Very limited resources
  • Crazy ideas about syncing with proprietary codebase
  • Being obsoleted by ath10k

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My current project: mt76

  • Driver for current MediaTek 802.11ac chipsets
  • Driver development contracted by MediaTek
  • Proprietary (but very small) firmware
  • Driver controls entire data path
  • Not as free as ath9k, but usable

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What’s wrong with ath10k?

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What’s wrong with ath10k?

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What’s wrong with ath10k?

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What’s wrong with ath10k?

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What’s wrong with ath10k?

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What about other vendors?

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What about other vendors?

  • Broadcom: main focus on fullmac devices, no progress on softmac
  • Marvell: comparable to ath10k, limited driver capabilities
  • Intel: too much firmware, very limited AP support
  • Realtek: limited driver capabilities

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Challenges and opportunities

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On chipset vendors

  • Educating chipset vendors is hard
  • Often not sustainable
  • Customer demand acts much faster
  • Can we engineer customer demand for free drivers?

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On chipset vendors

  • Educating chipset vendors is hard
  • Often not sustainable
  • Customer demand acts much faster
  • Can we engineer customer demand for free drivers?

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Customer demand

  • Educate big customers with enough volume
  • Provide good reference code and examples
  • Support GPL enforcement action

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The FCC mess

  • FCC noticed WiFi equipment interference with weather radar
  • Treats user access to flexible radio devices as a bug
  • New rules shifting responsibility to device vendors
  • Strong backlash from the tech community
  • Revised rules just as bad as original ones
  • Potential secondary gain for another spectrum user (LTE-U)
  • Similar problems in EU

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The FCC mess

  • FCC noticed WiFi equipment interference with weather radar
  • Treats user access to flexible radio devices as a bug
  • New rules shifting responsibility to device vendors
  • Strong backlash from the tech community
  • Revised rules just as bad as original ones
  • Potential secondary gain for another spectrum user (LTE-U)
  • Similar problems in EU

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Hardware lockdown

  • Chipset vendors considering hardware lockdown
  • Some router manufacturers already doing it
  • Provides a convenient excuse for not opening up
  • Also used for market segmentation

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What can we do?

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What can we do?

  • Spread the word on the FCC issue
  • Disclose security / design issues in existing products
  • Help write free 802.11 drivers
  • Create material to educate vendor decision makers
  • ...

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Questions?

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