Re: getting 10.1 amd64 onto a usb as mbr

[Steve Rikli <sr%genyosha.net@localhost>]

On Sat, Aug 30, 2025 at 10:19:03AM +0900, Henry wrote:
> I'm wanting to install 10.1 amd64 onto an older machine that can't
> handle efi.  Is there a cookbook, step-by-step instruction page
> somewhere to put the image on a mbr format usb?  I only seem to be
> able to put the image (NetBSD-10.1-amd64-install.img.gz) on an efi
> format usb.
> 
> I apologize for my slowness.  Age is catching up; that's for sure.
> TIA netbsd community.

If I understand your situation correctly, I think you simply want to
use the mbr-style img rather than the other one; reference:

https://cdn.netbsd.org/pub/NetBSD/NetBSD-10.1/amd64/INSTALL.html#Quick%20install%20notes%20for%20the%20impatient

... scroll down a bit to the part in the doc describing the boot images:

"Note the amd64 architecture has two images, NetBSD-10.1-amd64-install.img.gz
and NetBSD-10.1-amd64-bios-install.img.gz. The latter is intended for older
hardware which is unable to boot using a hybrid MBR and GPT image."

In your case, I think you'd use NetBSD-10.1-amd64-bios-install.img.gz for
USB boot media.

There are uncompressing and dd'ing notes in that same INSTALL doc, plus
an overall walkthrough for the sysinst procedure.

Cheers,
sr.