[SOLVED]After boot, how to know if it was BIOS or UEFI?

ewaller · 2015-05-13 14:18:52

At work, I have an Atom based System-On-Module on which am performing some power use analysis. Right now, I have no display -- nor am I likely to have one in the foreseeable future.

I have a breakout that gives me access to several USB ports and the wired Ethernet port. Working blind, I am able to boot a USB Arch Linux installation media. Sniffing the net I see it reach out and obtain an IP address from my DHCP server running on my other Arch box. After that, in the blind, I set the password and enable and start sshd. (USB keyboard)

Then, I can ssh into the Atom box. I have verified it is running the x86_64 Arch kernel from the install media (3.18.4-1). Cool.

Now, I am building an USB installation IAW https://wiki.archlinux.org/index.php/In … _a_USB_key. I am sure this SOM is not using secure boot, but it is not obvious as to whether it is booting in MBR or UEFI as (a) I cannot watch it, and (b) the media supports both methods. I need to decide how to configure my boot loader.

If there is no /sys/firmware/efi directory when booted from the install media, is it safe to assume the Atom booted using MBR?

Last edited by ewaller (2015-05-13 21:53:16)

mauritiusdadd · 2015-05-13 15:32:30

ewaller wrote:

If there is no /sys/firmware/efi directory when booted from the install media, is it safe to assume the Atom booted using MBR?

If there is no /sys/firmware/efi then it hasn't booted using UEFI.

mouseman · 2015-05-13 17:54:11

I was just curious (and somewhat bored) about these Atom SoC's when I read the EUFI wiki and The Atom SoC wiki pages.

I'd be surprised if you hadn't already read that but it says

Note: Intel Atom System-on-Chip systems ship with 32-bit UEFI (as on 2 November 2013). See this page for more info.

I don't know if that changes anything for you but I figured I'd let you know.

mauritiusdadd · 2015-05-13 18:04:31

mouseman wrote:

I was just curious (and somewhat bored) about these Atom SoC's when I read the EUFI wiki and The Atom SoC wiki pages.
I'd be surprised if you hadn't already read that but it says
Note: Intel Atom System-on-Chip systems ship with 32-bit UEFI (as on 2 November 2013). See this page for more info.
I don't know if that changes anything for you but I figured I'd let you know.

Yes, but it refers only to that versions which ship with Windows 8/8.1 32-bit and it says

these [systems] can be booted only using a 32-bit UEFI bootable USB, which is not provided by default in Archiso (official install iso) and Archboot.

But ewaller said he's running a x86_64 kernel using the default Arch install media, so this should not be the case.

ewaller · 2015-05-13 21:52:37

Sorry for not getting back earlier. Thank you both. Yes, it was not using UEFI. I had heard there were some that were using UEFI, but I missed the fact that USB media are a special case. I am still very new to this UEFI stuff. In any event, I did get it all to work. There was some ugliness with the boot loader configurations picking up the wrong UUID, or worse, making assumptions about drive configurations. Syslinux had problems finding its com 32 modules (never did figure that out)

Finally, I used the USB media to start a laptop, entered commands into the grub shell to get it to boot, reinstalled grub from real hardware rather than inside a VM with two levels of chroot environments. Aside from the boot loader setup, the actual Arch install went perfectly. When I got the boot loader (grub) to boot without intervention, I moved the USB back to the Atom and it worked on the first try. As we speak, the Atom is in a 40C environmental chamber happily reporting its core temperature to me in the other window (ssh and tmux) here on this desktop.

For the record, the junction (core) temperature is running just aver 10C above the chamber ambient temperature ( the kernel is reporting a value of 51C ).

Thanks for the help

Edit: Also, for the record, this is what a SoM looks like: http://www.congatec.com/us/products/qse … a-qa3.html

Last edited by ewaller (2015-05-14 02:25:33)

Arch Linux

#1 2015-05-13 14:18:52

[SOLVED]After boot, how to know if it was BIOS or UEFI?

#2 2015-05-13 15:32:30

Re: [SOLVED]After boot, how to know if it was BIOS or UEFI?

#3 2015-05-13 17:54:11

Re: [SOLVED]After boot, how to know if it was BIOS or UEFI?

#4 2015-05-13 18:04:31

Re: [SOLVED]After boot, how to know if it was BIOS or UEFI?

#5 2015-05-13 21:52:37

Re: [SOLVED]After boot, how to know if it was BIOS or UEFI?

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