beware CherryTrail and BayTrail systems

Over the last few years, Intel has been improving the Atom line of processors. Device manufacturers have been using these improved SoCs to create interesting low-end boxes. There are two marketing pushes: Android and Windows. Linux get a bit-part mention. All these processors are 64 bits but some have only 32-bit firmware (UEFI). None has a conventional old-style BIOS. Examples that I have some experience with: - Asus ZenPhone II cellphone (Android) (I think that later ZenPhones use ARM) - google nexus player (Android) - Asus transformer T100TAF (32-bit Windows) (convertible tablet/netbook) - Kangaroo little computer (64-bit Windows) - Dell Venue 8 Pro (5830) (32-bit Windows) - Acer Aspire E11 (ES1-11M-c0fq) notebook (64-bit Windows) - HP Pro Tablet 608 G1 (64-bit Windows) - for contrast: HP Stream Mini (64-bit Windows) (Haswell-based Celeron, not Atom) All these were about $200 or less -- kind of appealing. Good Linux experiences: - The Acer Aspire just worked under Linux. I don't know why. I have not tried HDMI-out: sound may not work under Linux. Sleep and all the other goodies do. I use it a lot. - The Kangaroo will boot Fedora easily. But I haven't tested much with it -- I use it in Windows 10 because of Netflix + Shomi mess. - HP Stream Mini just works. It is even possible to add RAM up to 16G and a 2.5 inch drive (with a magic cable that can be purchased from Hong Kong sellers). But it is Haswell, not *Trail. Bad Linux experiences: I don't really know an easy way of installing a normal Linux distro on an Android device. So I haven't tried. It takes hacking to get most Linux distros to boot under 32-bit UEFI. Now Ubuntu multiarch supports it out-of-the-box, things are starting to get better (as far as I'm concerned). There had already been projects to work around this limitation: <https://wiki.debian.org/InstallingDebianOn/Asus/T100TA> <https://www.happyassassin.net/fedlet-a-fedora-remix-for-bay-trail-tablets/> <https://plus.google.com/communities/117853703024346186936> and more. Even with that, there are plenty of problems with driver and power management support. The first link gives a nice scorecard. There is a kernel bug in handling cstates (compute states for power management) with BayTrail and CherryTrail. This has been around for over a year with no fix (initially it was thought to be a GPU driver bug). The bug appears to have been introduced by Intel. For the life of me, I don't know why they have not fixed it. <https://bugzilla.kernel.org/show_bug.cgi?id=109051> I haven't experienced this bug on my Acer notebook, possibly because I never watch videos on it. Intel created a driver to handle sound over HDMI but never upstreamed it so it no longer works. <https://01.org/ubuntu-hdmi> Most of these devices have 2G of RAM, 32G of eMMC (disk). This appears to be due to Microsoft licensing prices (free up to this size, expensive above). So there isn't really room for a dual-boot Windows/Linux setup. Before I install Linux, I want to try it to find if it works well enough on this hardware. On the T100TAF, there is a MicroSD drive. I thought that I could install Linux on that instead of replacing Windows on the eMMC. Amazingly, there is no UEFI driver for the MicroSD so the machine won't boot off MicroSD! debian 8.4.0's install disk doesn't see it either so I cannot install with most filesystems (except /boot) on the MicroSD. Incredible. CherryTrail is reputed to be very demanding of cooling and thus many systems suffer badly from thermal throttling (the chip slows down to cool off). This is true in Windows. I wonder how this works with Linux when cstates are constrained to avoid the bug mentioned above. The HP Pro Tablet 608 G1 was made for a much higher price-point (I lucked into a cheap unit from Factory Direct). It has 4G of RAM and 64G of eMMC. But it has it's own bugs under Windows that HP has been slow to fix. For my purposes, one problem is that there is only one USB C connector for power and for extra peripherals and HP won't let it act for more than one role at once (the whole point of USB C). They want me to buy a dock that connects to a proprietary POGO plug, for $200. No thanks. Summary: beware when buying a *Trail device thinking that you can just drop a normal Linux distro on it. Bonus warning: There are some problems with Linux support for Skylake, Intel's most recent generation of mainstream processors. I'm confident that they are being ironed out (Linus has a Skylake desktop).

- Acer Aspire E11 (ES1-11M-c0fq) notebook (64-bit Windows)
All these were about $200 or less -- kind of appealing.
Good Linux experiences:
- The Acer Aspire just worked under Linux. I don't know why. I have not tried HDMI-out: sound may not work under Linux. Sleep and all the other goodies do. I use it a lot.
I have an Acer Aspire laptop, E5-511-P8C8, setup to dual boot Windows 8.1 (ugh) and Linux Mint. HDMI out and sound work fine under Linux on this laptop. I can't think of anything that is problematic. I used it with a second screen GeChic 'On-Lap Monitor' 2501 series when I was on holiday in Guatemala and Got Some Real Work Done. Peter -- Peter Hiscocks Syscomp Electronic Design Limited, Toronto http://www.syscompdesign.com USB Oscilloscope and Waveform Generator 647-839-0325

| From: phiscock@ee.ryerson.ca | I have an Acer Aspire laptop, E5-511-P8C8, setup to dual boot Windows 8.1 | (ugh) and Linux Mint. I really dislike Acer's naming conventions. They don't tell me enough. And their website doesn't know this precise model. Their website does not appear to show specifications. It seems to have been sold by Best Buy, but it is no longer on their site. Perhaps the model was unique to Best Buy. They do that sometimes to avoid price matching. Here's a different E5-511. All I can assume is that it has similar characteristics. <http://www.acer.ca/ac/en/CA/content/model/NX.MPKAA.001> The processor is a Celereon N2930. It's a Bay Trail processor. Since it came with 4G of RAM, I assume that it comes with 64-bit UEFI and 64-bit Windows (32-bit consumer versions of Windows don't support more than about 3G of RAM). And perhaps even an ability to do legacy MBR booting and a CSM to support BIOS calls. Since it came with 4G of RAM, the Windows license was not free to Acer. This puts your notebook in a significantly higher price range than my Acer netbook. | HDMI out and sound work fine under Linux on this laptop. I can't think of | anything that is problematic. It seems that some Acer BayTrail notebooks (like yours and mine) work fine with Linux. I'm not sure why. The processor marketing families are different from the problematic ones. The Acer notebooks are using Celeron N2840 and N2930. The other BayTrail things have processors called Atom Z3735F and the like. I just tried HDMI out and sound on my Acer netbook. Both worked well. Going from 11.6" to 39" was a bit startling. It could only drive the display at 1920x1080, not 3840x2160. At least some CherryTrails can do UltraHD. I cannot easily test those other boxes.
participants (2)
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D. Hugh Redelmeier
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phiscock@ee.ryerson.ca