Does rEFInd support USB-OTG as boot device?

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I'm having a hard time at installing Ubuntu on my Acer Iconia W10 Tablet. I modified boot priority to:

  1. USB Stick/HDD
  2. USB CD/DVD reader
  3. The so-called "Windows Boot Manager" (as unclear as this)

Even with SecureBoot disabled, my tablet refuses to display USB devices in boot menu. I even tried with a Windows 10 installation disk, nothing. It's a it has an x86_32 Intel Atom Processor, Windows 8, EFI only support and it has no "proper" USB port, just a Type B Micro USB port that is used as host through an OTG cable. (yeah, exactly, just like your Android phone, except this is no phone.)

According to Acer forums, it is possible to boot from USB devices using the default bootloader on Acer Iconia W10.

Windows Boot Manager is driving me crazy, so I'm considering to install a separate Boot Manager (rEFInd) to make it easier for me to boot from USB.

Supposing I'll be able to install rEFInd and it will boot correctly, will it work with USB pendrives connected via OTG?

Also, will it be necessary to disable Windows Secure Boot feature?

Manchineel

Posted 2016-09-18T18:19:04.303

Reputation: 479

When you say that "according to forums, it is possible to boot from USB dev", do you mean "it is possible in general" (which is undoubtedly true), or the particular "Acer Iconia" with particular version of UEFI/BIOS was able to boot from some USB device? – Ale..chenski – 2016-09-18T19:31:04.747

Sorry for not being clear, I updated my question now – Manchineel – 2016-09-18T19:38:06.830

Again, instead of saying "I'm having a hard time at installing Ubuntu...", could you better describe what steps you are going through, and what is system response to your attempts at each point? – Ale..chenski – 2016-09-18T19:40:43.910

How your USB drive is formatted? It must be FAT32 clean format, with no Linux hidden partitions. – Ale..chenski – 2016-09-18T19:47:59.993

Sure. FAT32, MSDOS partition table, made with unetbootin – Manchineel – 2016-09-18T19:49:22.510

Also, are you sure that the "formally illegal micro-B (not A/B!) connector" changes its role to HOST mode? Do you see VBUS coming at 5V and powers your pen drive? Are you using an unconventional micro-B to USB-A "OTG adapter" to connect? – Ale..chenski – 2016-09-18T19:50:51.107

Can you start UEFI shell? Can you see USB volume mounted somehow? – Ale..chenski – 2016-09-18T19:57:28.183

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  • It is kinda weird. It has a micro-USB connector that acts as host when I connect a USB device through an OTG cable. I have plugged in a DVD reader that powers from the same cable as data transfer (single port on it), for example: the DVD spins, the disc opens in explorer.exe and other Apps, I'm able to play it from VLC. So yeah, it has enough power. The only thing is that I did not yet figure out what the Micro USB port does as hub. (the OTG cable was included in the box)
    • < – Manchineel – 2016-09-20T11:46:06.867

    UEFI shell is a subsystem of initial boot, similar to BIOS. It is a mini-OS of BIOS. You can't access it from Windows. To access your drive from UEFI/BIOS, USB support must be embedded into UEFI/BIOS, which is not a given. More, all this stuff is overly complicated, and it is very likely that Acer did not implement the OTG switch correctly in the BIOS. Does your BIOS have any option to enter UEFI shell? Can you enter "Setup" before booting into Windows? If you are not familiar with the distinction between UEFI/BIOS and a bootable OS, then "eEFInd" likely is of no help to you. – Ale..chenski – 2016-09-20T16:24:32.207

    rEFInd is a boot manager I use to graphically see all bootloaders located on any drive and start them. I have no access to the shell from the BIOS. The BIOS is extremely and ridiculously "customized": it has a complete GUI with mouse and touchscreen support, and an Acer logo on the top. They did not only make it fool proof, they also removed some features such as UEFI shell. On the online manual, it talks about "connecting a USB DVD reader via OTG to reinstall Windows". And there's an entry for USB drive in boot priority settings. – Manchineel – 2016-09-20T17:12:29.997

    There should be some secret back door, something like holding Vol_up and Vol-Down simultaneously when pressing Power Button. But who knows. An entry in boot menu does not necessarily mean that any particular USB drive is recognized by BIOS. When you plug a USB drive into your hub (I presume you must use a hub to have your mouse), do you have any means to detect USB activity on that drive? – Ale..chenski – 2016-09-20T18:06:24.570

    I am not using a Hub, I'm using the touchscreen that thanks to some trick/blackmagic works in BIOS. USB drives are not detected while I am in the boot menu (F12). – Manchineel – 2016-09-22T18:45:07.820

    So the question is, is your USB port in host mode when you are in BIOS/UEFI/whatever? Normal config in the case of a single-port tablet is "OTG adapter/dongle" + USB hub + keyboard + mouse + pen drive. So, the quesion again: do you have any way to determine if the tablet port is in host mode when you are in BIOS? At least can you check if VBUS is coming active at +5V? – Ale..chenski – 2016-09-22T18:57:47.933

    >

  • Keyboard hooks up with proprietary port on the bottom, even acts as a power bank.
    • < – Manchineel – 2016-09-22T19:46:50.343

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  • When in BIOS or UEFI boot menu, the USB DVD reader I also tried starts spinning, reads (or does something I don't know) then stops, with power LED still on
    • < – Manchineel – 2016-09-22T19:48:17.203

    It is possible that your system looks for special proprietary formatted partitions on the media (DVD or flash drive), and if not found, it does not recognize the media. Without USB protocol analyzer on your OTG port, or at least some USB bus monitor, it is impossible to diagnose. – Ale..chenski – 2016-09-22T20:06:30.210

    Answers

    1

    rEFInd relies on the EFI firmware to access hardware and read the filesystems they contain. In theory, if the firmware can access the device and read any filesystem(s) on it, rEFInd should be able to boot boot loaders on those devices and filesystems. rEFInd doesn't know or care about cable types or even whether a device is a USB device, a SATA drive, etc. (rEFInd does try to determine whether a device is a removable or non-removable disk, and to identify optical media as such, but that's mainly just to add an appropriate badge for each type of device -- but see below.) Thus, the answer to the question of whether rEFInd supports your medium is "it depends on the computer." I've seen some tablet-type computers that can't boot from some media because the EFI doesn't support those media. Other computers can boot from anything.

    That said, there's always the possibility of a bug in rEFInd that will cause it to misbehave with some types of media. I'm not aware of any such bugs at the present time, though. (Note that I maintain rEFInd.)

    One more caveat is that rEFInd does support limiting its scans to particular types of disks. This is done via the scanfor line in refind.conf. You can set options to scan for internal, external, and optical media; and each of those for BIOS/CSM/legacy-mode and EFI/UEFI-mode. The default is to scan for all three media in EFI mode on UEFI-based PCs, and for all six types on Macs. You can limit (or expand) scans by uncommenting the scanfor line and adjusting its options. (There's also an option for network booting via PXE.) The default option is appropriate for most systems, but if it's been changed, you might not see some media appear.

    Rod Smith

    Posted 2016-09-18T18:19:04.303

    Reputation: 18 427

    I was curious, which are the other three types of media on Mac? – Manchineel – 2017-02-07T20:24:22.470

    rEFInd explicitly codes for internal, external, and optical media. In refind.conf, each of those has two names for use with the scanfor line, one for EFI-mode booting and one for BIOS-mode booting. There's also the netboot option (for network booting) and manual (for manual boot stanzas). That's a total of eight scanfor options that cover three physical media types (four if you count network booting as a separate medium). These are all identical for Macs and PCs, although the BIOS-mode boot options are handled differently on each platform. – Rod Smith – 2017-02-09T19:32:57.893

    Asked: 2016-09-18T18:19:04.303

    Viewed: 714 times

    Active: 2016-10-21T14:32:17.540