Mailing List Archive: sysrescue+new asus mobo+secure boot=0

sysrescue+new asus mobo+secure boot=0

john.blinka at gmail

May 11, 2021, 3:08 PM

Post #1 of 22 (1437 views)

Hello, Gentooers,

I just acquired a new Asus board (b560m tuf gaming+wifi) to replace a
failed gigabyte board on my main Gentoo machine. Assembly went well, it
powered up flawlessly first time, it recognized all the hardware... and
then nothing. Cannot get it to boot.

On all my other machines, there’s a bios setting that allows me to turn off
secure boot, which allows me to boot Sysrescue from usb, or Gentoo from a
hard drive.

Not so (as far as I can tell) on this mobo/bios. There’s the usual bios
boot menu and a secure boot submenu. However, the secure boot submenu only
allows me to select between Windows UEFI (with, presumably, secure boot
enabled) and “other OS”. I have no clue what “other OS” implies about
secure boot. It also offers the ability to accept the standard
Microsoft-supplied secure boot keys, or to change or delete them. There
are a few claims on the web that clearing the PK key (and only that key) or
clearing all of the keys is the way to turn off secure boot. I’ve tried
all the combinations; none of them allow me to boot.

The farthest I’ve gotten is to display the Sysrescue usb boot choices.
Selecting any of them seems to (briefly, for a second) start a boot and
then the screen goes blank. Nothing after that.

I haven’t found any mention on the web that Asus boards are particularly
linux hostile, nor much discussion implying that turning off secure boot is
particularly tricky. Most of what I’ve seen is, say, Ubuntu oriented. I
gather that they have gone through the process of getting their secure boot
keys authorized by Microsoft.

Anybody have success getting Gentoo to boot from a recent Asus mobo?

Thanks!

John Blinka

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

thelma at sys-concept

May 11, 2021, 3:49 PM

Post #2 of 22 (1437 views)

On 5/11/21 4:08 PM, John Blinka wrote:
> Hello, Gentooers,
>
> I just acquired a new Asus board (b560m tuf gaming+wifi) to replace a failed gigabyte board on my main Gentoo machine. Assembly went well, it powered up flawlessly first time, it recognized all the hardware... and then nothing. Cannot get it to boot.
>
> On all my other machines, there’s a bios setting that allows me to turn off secure boot, which allows me to boot Sysrescue from usb, or Gentoo from a hard drive.
>
> Not so (as far as I can tell) on this mobo/bios. There’s the usual bios boot menu and a secure boot submenu. However, the secure boot submenu only allows me to select between Windows UEFI (with, presumably, secure boot enabled) and “other OS”. I have no clue what “other OS” implies about secure boot. It also offers the ability to accept the standard Microsoft-supplied secure boot keys, or to change or delete them. There are a few claims on the web that clearing the PK key (and only that key) or clearing all of the keys is the way to turn off secure boot. I’ve tried all the combinations; none of them allow me to boot.
>
> The farthest I’ve gotten is to display the Sysrescue usb boot choices. Selecting any of them seems to (briefly, for a second) start a boot and then the screen goes blank. Nothing after that.
>
> I haven’t found any mention on the web that Asus boards are particularly linux hostile, nor much discussion implying that turning off secure boot is particularly tricky. Most of what I’ve seen is, say, Ubuntu oriented. I gather that they have gone through the process of getting their secure boot keys authorized by Microsoft.
>
> Anybody have success getting Gentoo to boot from a recent Asus mobo?
>
> Thanks!
>
> John Blinka

Try to watch this clip it might help.

https://www.google.com/search?sxsrf=ALeKk039uHXT9NuDloVx1Rvp0Mw3kBzEXg:1620773038736&q=asus+board+%22b560m%22+turn+off+secure+boot&sa=X&ved=2ahUKEwjSsfCJ2sLwAhXCpJ4KHdr6Bz4Q5t4CMAx6BAgeEA0&biw=1263&bih=660#kpvalbx=_ygibYJexK87E-gT-gLaYDw55

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

kaliman.mike at gmail

May 11, 2021, 5:56 PM

Post #3 of 22 (1437 views)

I have an Asus TUF Gaming X570 and have the secure boot OS type as "Other
OS". I've been using rEFInd to dual boot with Windows.

On Tue, May 11, 2021, 6:49 PM <thelma@sys-concept.com> wrote:

> On 5/11/21 4:08 PM, John Blinka wrote:
> > Hello, Gentooers,
> >
> > I just acquired a new Asus board (b560m tuf gaming+wifi) to replace a
> failed gigabyte board on my main Gentoo machine. Assembly went well, it
> powered up flawlessly first time, it recognized all the hardware... and
> then nothing. Cannot get it to boot.
> >
> > On all my other machines, there’s a bios setting that allows me to turn
> off secure boot, which allows me to boot Sysrescue from usb, or Gentoo from
> a hard drive.
> >
> > Not so (as far as I can tell) on this mobo/bios. There’s the usual bios
> boot menu and a secure boot submenu. However, the secure boot submenu only
> allows me to select between Windows UEFI (with, presumably, secure boot
> enabled) and “other OS”. I have no clue what “other OS” implies about
> secure boot. It also offers the ability to accept the standard
> Microsoft-supplied secure boot keys, or to change or delete them. There
> are a few claims on the web that clearing the PK key (and only that key) or
> clearing all of the keys is the way to turn off secure boot. I’ve tried
> all the combinations; none of them allow me to boot.
> >
> > The farthest I’ve gotten is to display the Sysrescue usb boot choices.
> Selecting any of them seems to (briefly, for a second) start a boot and
> then the screen goes blank. Nothing after that.
> >
> > I haven’t found any mention on the web that Asus boards are particularly
> linux hostile, nor much discussion implying that turning off secure boot is
> particularly tricky. Most of what I’ve seen is, say, Ubuntu oriented. I
> gather that they have gone through the process of getting their secure boot
> keys authorized by Microsoft.
> >
> > Anybody have success getting Gentoo to boot from a recent Asus mobo?
> >
> > Thanks!
> >
> > John Blinka
>
> Try to watch this clip it might help.
>
>
> https://www.google.com/search?sxsrf=ALeKk039uHXT9NuDloVx1Rvp0Mw3kBzEXg:1620773038736&q=asus+board+%22b560m%22+turn+off+secure+boot&sa=X&ved=2ahUKEwjSsfCJ2sLwAhXCpJ4KHdr6Bz4Q5t4CMAx6BAgeEA0&biw=1263&bih=660#kpvalbx=_ygibYJexK87E-gT-gLaYDw55
>
>

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 5:39 AM

Post #4 of 22 (1437 views)

On Tue, May 11, 2021 at 6:49 PM <thelma@sys-concept.com> wrote:
<snip>

>
> Try to watch this clip it might help.
>
>
> https://www.google.com/search?sxsrf=ALeKk039uHXT9NuDloVx1Rvp0Mw3kBzEXg:1620773038736&q=asus+board+%22b560m%22+turn+off+secure+boot&sa=X&ved=2ahUKEwjSsfCJ2sLwAhXCpJ4KHdr6Bz4Q5t4CMAx6BAgeEA0&biw=1263&bih=660#kpvalbx=_ygibYJexK87E-gT-gLaYDw55
>
> Thanks for the additional resources. Unfortunately, I’ve already tried
what these posts suggest, but without success.

John

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 5:43 AM

Post #5 of 22 (1437 views)

On Tue, May 11, 2021 at 8:57 PM Mike Kaliman <kaliman.mike@gmail.com> wrote:

> I have an Asus TUF Gaming X570 and have the secure boot OS type as "Other
> OS". I've been using rEFInd to dual boot with Windows.
>

So, this suggests that “Other OS” was sufficient to allow you to boot some
kind of Linux distro, which you then used to install Gentoo. I take that
as proof of concept that what I’ve tried *ought* to work.

Thanks for that reassurance!

John

>

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 5:56 AM

Post #6 of 22 (1437 views)

Thanks for the suggestions for solving my booting problem, which admittedly
is not particularly Gentoo related at this stage in the installation
process.

I’ve tried usb sticks with both Sysrescue and Ubuntu server to boot this
thing. It appears to attempt to boot each one, but then the screen goes
blank after 1-2 seconds, at which point I can’t tell what’s going on. Each
usb stick boots my other machines normally, and the screen works normally
when used as a display for my other Gentoo machines.

Your suggestions imply that there’s nothing especially magical about
putting Linux on Asus mobos and that I’m setting up the bios correctly. So
I’m coming to the conclusion that this mobo may not be working as
intended. Back it goes!

John

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

kaliman.mike at gmail

May 12, 2021, 6:00 AM

Post #7 of 22 (1437 views)

I think I had used the Gentoo live USB originally, although I've the
gparted live USB as well. Sysrescue ought to work but I'm wondering if
there's an issue with a missing GPU driver or something. Granted, id be
surprised that both sysrescue and the Ubuntu server USBs are missing
drivers.

What is your graphics setup? Integrated? Dedicated?

On Wed, May 12, 2021, 8:43 AM John Blinka <john.blinka@gmail.com> wrote:

>
>
> On Tue, May 11, 2021 at 8:57 PM Mike Kaliman <kaliman.mike@gmail.com>
> wrote:
>
>> I have an Asus TUF Gaming X570 and have the secure boot OS type as "Other
>> OS". I've been using rEFInd to dual boot with Windows.
>>
>
> So, this suggests that “Other OS” was sufficient to allow you to boot some
> kind of Linux distro, which you then used to install Gentoo. I take that
> as proof of concept that what I’ve tried *ought* to work.
>
> Thanks for that reassurance!
>
> John
>
>>

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

antlists at youngman

May 12, 2021, 6:15 AM

Post #8 of 22 (1437 views)

On 12/05/21 13:43, John Blinka wrote:
>
>
> On Tue, May 11, 2021 at 8:57 PM Mike Kaliman <kaliman.mike@gmail.com
> <mailto:kaliman.mike@gmail.com>> wrote:
>
> I have an Asus TUF Gaming X570 and have the secure boot OS type as
> "Other OS". I've been using rEFInd to dual boot with Windows.
>
>
> So, this suggests that “Other OS” was sufficient to allow you to boot
> some kind of Linux distro, which you then used to install Gentoo. I
> take that as proof of concept that what I’ve tried *ought* to work.
>
So what I guess *might* be happening is that there is a signed
boot-loader on the "other OS" on CD, but because the gentoo boot loader
is not signed, that's why it's not working ...

So somehow you need to get your "other linux" booted again, get back
into gentoo, and install a signed binary boot loader. Pain in the Arse!!!

Cheers,
Wol

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

markknecht at gmail

May 12, 2021, 6:49 AM

Post #9 of 22 (1437 views)

On Wed, May 12, 2021 at 6:04 AM Wols Lists <antlists@youngman.org.uk> wrote:
>
> On 12/05/21 13:43, John Blinka wrote:
> >
> >
> > On Tue, May 11, 2021 at 8:57 PM Mike Kaliman <kaliman.mike@gmail.com
> > <mailto:kaliman.mike@gmail.com>> wrote:
> >
> > I have an Asus TUF Gaming X570 and have the secure boot OS type as
> > "Other OS". I've been using rEFInd to dual boot with Windows.
> >
> >
> > So, this suggests that “Other OS” was sufficient to allow you to boot
> > some kind of Linux distro, which you then used to install Gentoo. I
> > take that as proof of concept that what I’ve tried *ought* to work.
> >
> So what I guess *might* be happening is that there is a signed
> boot-loader on the "other OS" on CD, but because the gentoo boot loader
> is not signed, that's why it's not working ...
>
> So somehow you need to get your "other linux" booted again, get back
> into gentoo, and install a signed binary boot loader. Pain in the Arse!!!
>
> Cheers,
> Wol
>

I suspect the OP has seen these but I'll post them anyway in case they
haven't popped up yet:

https://wiki.gentoo.org/wiki/User:Sakaki/Sakaki%27s_EFI_Install_Guide/Creating_and_Booting_the_Minimal-Install_Image_on_USB#turn_off_secure_boot

https://wiki.gentoo.org/wiki/User:Sakaki/Sakaki%27s_EFI_Install_Guide/Configuring_Secure_Boot

I'm at the point where I'm looking at building a new machine and being a
long-time Asus user I'm pained seeing the pain being inflicted.

- Mark

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

neil at digimed

May 12, 2021, 7:21 AM

Post #10 of 22 (1437 views)

On Wed, 12 May 2021 08:56:16 -0400, John Blinka wrote:

> Thanks for the suggestions for solving my booting problem, which
> admittedly is not particularly Gentoo related at this stage in the
> installation process.
>
> I’ve tried usb sticks with both Sysrescue and Ubuntu server to boot this
> thing. It appears to attempt to boot each one, but then the screen goes
> blank after 1-2 seconds, at which point I can’t tell what’s going on.

This could possibly be KMS kicking in, try adding nomodeset to the boot
options. While you're editing the boot options, you may as well remove
any quiet or splash options too, so you can better see what is going on.

--
Neil Bothwick

"We demand rigidly defined areas of doubt and uncertainty!"

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 9:56 AM

Post #11 of 22 (1437 views)

On Wed, May 12, 2021 at 9:04 AM Wols Lists <antlists@youngman.org.uk> wrote:

> On 12/05/21 13:43, John Blinka
> >
> So what I guess *might* be happening is that there is a signed
> boot-loader on the "other OS" on CD, but because the gentoo boot loader
> is not signed, that's why it's not working ...
>
> So somehow you need to get your "other linux" booted again, get back
> into gentoo, and install a signed binary boot loader. Pain in the Arse!!!
>
> Cheers,
> Wol
>
>
> “Other OS” is a secure boot setting in the Asus bios. There has never been
*any* actual os running on this board, since I have never gotten anything
to boot.

I suspected that sysrescue and Gentoo do not have signed boot loaders on
their isos (does Gentoo even have isos? Haven’t used anything but sysrescue
in ages…). That’s why I downloaded and tried the current Ubuntu server
iso, believing that it would have a signed boot loader. That didn’t boot.

John

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 10:10 AM

Post #12 of 22 (1437 views)

On Wed, May 12, 2021 at 10:22 AM Neil Bothwick <neil@digimed.co.uk> wrote:

> On Wed, 12 May 2021 08:56:16 -0400, John Blinka wrote:
>
> >
> > I’ve tried usb sticks with both Sysrescue and Ubuntu server to boot this
> > thing. It appears to attempt to boot each one, but then the screen goes
> > blank after 1-2 seconds, at which point I can’t tell what’s going on.
>
> This could possibly be KMS kicking in, try adding nomodeset to the boot
> options. While you're editing the boot options, you may as well remove
> any quiet or splash options too, so you can better see what is going on.

KMS… had to Google that. Not that I am fluent in this stuff
(understatement!) but how does one add nomodeset to boot options, or edit
boot options? The world I’m living in consists of downloading a bootable
Linux iso image, dd’ing it to a usb stick, then trying to boot my
recalcitrant Asus board from that. What you’re suggesting sounds to me
like rolling my own Gentoo usb boot stick. Is
https://wiki.gentoo.org/wiki/Install_Gentoo_on_a_bootable_USB_stick is the
place to go for that?

John

Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 10:13 AM

Post #13 of 22 (1437 views)

On Wed, May 12, 2021 at 9:01 AM Mike Kaliman <kaliman.mike@gmail.com> wrote:

> I think I had used the Gentoo live USB originally, although I've the
> gparted live USB as well. Sysrescue ought to work but I'm wondering if
> there's an issue with a missing GPU driver or something. Granted, id be
> surprised that both sysrescue and the Ubuntu server USBs are missing
> drivers.
>
> What is your graphics setup? Integrated? Dedicated?
>

Integrated intel.

John

>

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

neil at digimed

May 12, 2021, 10:34 AM

Post #14 of 22 (1437 views)

On Wed, 12 May 2021 13:10:56 -0400, John Blinka wrote:

> > This could possibly be KMS kicking in, try adding nomodeset to the
> > boot options. While you're editing the boot options, you may as well
> > remove any quiet or splash options too, so you can better see what is
> > going on.
>
>
> KMS… had to Google that. Not that I am fluent in this stuff
> (understatement!) but how does one add nomodeset to boot options, or
> edit boot options?

Press e at the boot menu, that's the usual key to edit the boot options.
You may have to press a key, usually space, to bring up the boot menu,
depending on the ISO you are using.

I'd be surprised to find that "Other OS" is a secure boot option, it
sounds like the option to run without secure boot.

--
Neil Bothwick

I don't know if I can assimilate one more Borg Tagline!

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

waltdnes at waltdnes

May 12, 2021, 10:42 AM

Post #15 of 22 (1437 views)

On Wed, May 12, 2021 at 01:10:56PM -0400, John Blinka wrote

> but how does one add nomodeset to boot options, or edit boot options?

The default ISO USB action is to wait a few seconds and then boot the
standard kernel. Tap "any key" (e.g. spacebar) ***BEFORE THE WAIT TIMES
OUT*** and then type in the line...

gentoo nomodeset

...followed by the {ENTER} key. That should boot with the nomodeset
option.

--
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 2:29 PM

Post #16 of 22 (1437 views)

On Wed, May 12, 2021 at 1:35 PM Neil Bothwick <neil@digimed.co.uk> wrote:

> On Wed, 12 May 2021 13:10:56 -0400, John Blinka wrote:
>
> > Not that I am fluent in this stuff
> > (understatement!) but how does one add nomodeset to boot options, or
> > edit boot options?
>
> Press e at the boot menu, that's the usual key to edit the boot options.
> You may have to press a key, usually space, to bring up the boot menu,
> depending on the ISO you are using.

Cool! I’ve been linuxing for decades and never had the need to do this.
Until now. Sysrescue booted (has probably been booting all along) *and*
with nomodeset applied I can now see what it’s doing on the monitor. Now
that I’m on terra firma, hope it will be clear sailing from here.
(Apologies for the clash of metaphors!).

>
>
> I'd be surprised to find that "Other OS" is a secure boot option, it
> sounds like the option to run without secure boot.

Perhaps. That will be one of my experiments once I get things working.

John

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 2:31 PM

Post #17 of 22 (1437 views)

On Wed, May 12, 2021 at 1:42 PM Walter Dnes <waltdnes@waltdnes.org> wrote:

> On Wed, May 12, 2021 at 01:10:56PM -0400, John Blinka wrote
>
> > but how does one add nomodeset to boot options, or edit boot options?
>
> The default ISO USB action is to wait a few seconds and then boot the
> standard kernel. Tap "any key" (e.g. spacebar) ***BEFORE THE WAIT TIMES
> OUT*** and then type in the line...
>
> gentoo nomodeset
>
> ...followed by the {ENTER} key. That should boot with the nomodeset
> option

Thanks - works like a charm! (And I learned something new.)

John

>
>

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 12, 2021, 4:51 PM

Post #18 of 22 (1437 views)

On Wed, May 12, 2021 at 5:29 PM John Blinka <john.blinka@gmail.com> wrote:

>
>
> On Wed, May 12, 2021 at 1:35 PM Neil Bothwick <neil@digimed.co.uk> wrote:
>
>>
>> I'd be surprised to find that "Other OS" is a secure boot option, it
>> sounds like the option to run without secure boot.
>
>
> Perhaps. That will be one of my experiments once I get things working.
>

And it appears your intuition is correct. I left all the “secure boot”
options in the bios at their defaults except one. I changed “OS Type” from
“Windows UEFI mode” to “Other OS”. That was sufficient to boot from my
Sysrescue usb.

John

>

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

waltdnes at waltdnes

May 12, 2021, 7:25 PM

Post #19 of 22 (1437 views)

On Wed, May 12, 2021 at 05:31:56PM -0400, John Blinka wrote
> On Wed, May 12, 2021 at 1:42 PM Walter Dnes <waltdnes@waltdnes.org> wrote:
>
> > On Wed, May 12, 2021 at 01:10:56PM -0400, John Blinka wrote
> >
> > > but how does one add nomodeset to boot options, or edit boot options?
> >
> > The default ISO USB action is to wait a few seconds and then boot the
> > standard kernel. Tap "any key" (e.g. spacebar) ***BEFORE THE WAIT TIMES
> > OUT*** and then type in the line...
> >
> > gentoo nomodeset
> >
> > ...followed by the {ENTER} key. That should boot with the nomodeset
> > option
>
>
> Thanks - works like a charm! (And I learned something new.)

I should add...

1) you can enter multiple parameters on the commandline, separated by a
space. For an incomplete list of boot parameters, scroll through...
https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html

2) these instructions work for a LILO boot. On a GRUB boot system, if
you want to add one-time kernel boot parameter(s), see...
https://wiki.ubuntu.com/Kernel/KernelBootParameters for instructions.

--
Walter Dnes <waltdnes@waltdnes.org>
I don't run "desktop environments"; I run useful applications

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

antlists at youngman

May 13, 2021, 10:02 AM

Post #20 of 22 (1437 views)

On 13/05/2021 00:51, John Blinka wrote:
> And it appears your intuition is correct. I left all the “secure boot”
> options in the bios at their defaults except one. I changed “OS Type”
> from “Windows UEFI mode” to “Other OS”. That was sufficient to boot
> from my Sysrescue usb.

One other little point of interest ... so does that mean
non-windows-uefi, or does it mean bios legacy?

That could be important information at some point, especially if you
want to dual-boot.

Cheers,
Wol

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

kaliman.mike at gmail

May 13, 2021, 10:07 AM

Post #21 of 22 (1437 views)

I boot with UEFI using that setting so i assume it means non-Windows-UEFI,
weird.
I've been booting Windows and Gentoo without issue so Other OS should be
fine for that.

On Thu, May 13, 2021, 1:03 PM antlists <antlists@youngman.org.uk> wrote:

> On 13/05/2021 00:51, John Blinka wrote:
> > And it appears your intuition is correct. I left all the “secure boot”
> > options in the bios at their defaults except one. I changed “OS Type”
> > from “Windows UEFI mode” to “Other OS”. That was sufficient to boot
> > from my Sysrescue usb.
>
> One other little point of interest ... so does that mean
> non-windows-uefi, or does it mean bios legacy?
>
> That could be important information at a some point, especially if you
> want to dual-boot.
>
>
> Cheers,
> Wol
>
>

Re: Re: sysrescue+new asus mobo+secure boot=0 [ In reply to ]

john.blinka at gmail

May 13, 2021, 2:49 PM

Post #22 of 22 (1437 views)

On Thu, May 13, 2021 at 1:03 PM antlists <antlists@youngman.org.uk> wrote:

> On 13/05/2021 00:51, John Blinka wrote:
> > And it appears your intuition is correct. I left all the “secure boot”
> > options in the bios at their defaults except one. I changed “OS Type”
> > from “Windows UEFI mode” to “Other OS”. That was sufficient to boot
> > from my Sysrescue usb.
>
> One other little point of interest ... so does that mean
> non-windows-uefi, or does it mean bios legacy?
>
> That could be important information at some point, especially if you
> want to dual-boot.

Don’t know for sure. Suspect it’s non-windows-uefi. There’s a separate
option in the bios boot submenu called CSM (Compatibility Support Module).
Googling this suggests to me that this is the bios legacy switch. I’ve
moved on to uefi exclusively, am beginning to get a grip on it, and will
not dual boot on this box.

John

>
>