Ask the Experts - ARM Fellow Jem Davies Answers Your GPU Questions

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• milli - Wednesday, July 2, 2014 - link

  Thank you. This info is much appreciated.

• cwabbott - Wednesday, July 2, 2014 - link

  In the Midgard instruction set, what are the even-numbered bits starting at 18 of the ALU control word used for? We know that the odd-numbered ones are for controlling which ALU's in the pipeline are used, but it seems rather mysterious that only every other bit is used.

• JemDavies - Thursday, July 3, 2014 - link

  Hi everyone - I just wanted to say thank you for the opportunity to answer your great questions this week. If you ever have any questions re: Mali or anything else related to ARM, the fastest way to get them answered is to follow @ARMPROffice and submit your questions via Twitter.

• libv - Friday, July 4, 2014 - link

  So i take it that you will not be answering questions from late wednesday on?

• elabdump - Friday, July 4, 2014 - link

  Would free drivers gives greater value to the shareholders of ARM?

• libv - Saturday, July 5, 2014 - link

  Since Mr Davies is apparently no longer available, here are my views as the lima driver developer, the person who started the open ARM GPU drivers movement, the pesky hacker who pointed out the flaws in RPi foundation "open source" press release, leading to a proper open source strategy there, and one of the key players in open sourcing AMD Radeon graphics hardware.
  
  Yes, free drivers would mean greater value to shareholders.
  * Marketing: at the time, ARM would've been the first to embrace open source drivers, and this would've given them a nice marketing boost. Broadcom has now ran away with that. Then there is the fact that the competition has free drivers. First and foremost, intel, which has a massive and growing team of open source developers. ARM today doesn't hold a candle to that.
  * ODM and SoC vendor satisfaction: Open source drivers, when done right and with sufficient support (which is still cheap compared to the binary only route), would severely reduce the integration and legal overhead for device makers and SoC vendors. The ability to grab a set of open source projects immediately, versus having to deal with account managers and lawyers and NDAs, and the ability to report issues directly and openly, and immediately profiting from advances or fixes from the rest of the community would severely reduce the overhead of bringing up new platforms or new devices. An open source strategy directly benefits ARM customers and will lead to increased sales and returning customers (who are less likely to jump ship, like Allwinner just did).
  * Consumer satisfaction: Cyanogenmod is the perfect example here. After market support for mobile devices is important and growing in importance, it won't be long before consumers buy devices based on prospective aftermarket support. Open source drivers are a key enabler for cyanogenmod, and would severely improve the quality of CM while reducing overhead.
  * While not as dominating a reason, alternative uses of ARM SoCs (like the raspberry pi is showing us, and like the OSHW boards from olimex) are becoming more important. These development boards allow a wide array of projects, and will spearhead all new developments, perhaps opening up whole new markets. Binary only drivers currently severely limit the feasibility or practicality of such projects.
  * ARM is going to try to muscle in on the server market. Their 64bit processors will function more like a PC, in that you will not require a board specific bootloader anymore. Lack of open source drivers will be holding this platform back, just like it did for AMD back when it bought ATI.
  * Then there is topics like GPGPU/Compute and many other corners which my synapses cannot recall off hand...
  
  None of the above has so far convinced Mr Davies, neither has the fact that an open source strategy based on my lima driver would be highly credible, up and running quickly, and very cheap (6 manyears/year is what i projected initially). But Mr Davies has repeatedly rejected the idea of an open source driver for the mali family, even though my information is that the engineers in his department tend to not agree with him on this.
  
  With Broadcom now doing a proper open source GPU driver, the question really becomes: Does ARMs lack of free drivers hurt shareholder value?

• przemo_li - Monday, July 7, 2014 - link

  You have also forgotten, that community IS NOT political.
  
  Eg. on desktop side we see cross adoption of vendor specific extension/features when it make sense, in open source drivers. (VDPAU for video which is Nvidia child, AMD_performance_monitor for performance counter reporting, etc.) Thats good as it prevent Vendors from harming their own hw by limiting sw capabilities.
  
  (And really determined partners can just hire somebody to implement what they really need, or thing would give Mali competitive edge, no reliance on ARM blessing, which is good to ARM in the long run)

• elabdump - Tuesday, July 8, 2014 - link

  Even Nvidia takes another route with ARM based GPUs. Customers get less overhead by choosing not Mali as GPU.

• brendon919 - Wednesday, July 23, 2014 - link

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