AMD using legacy BIOS? [SOLVED]

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

I just built an AMD based machine and will soon be installing Gentoo. One thing for sure is that I want to use syslinux instead of grub 2...absolutely detest that whole generated config stuff in grub 2 and have been using syslinux on my old systems for years. I have no need for any dual boot etc, and was considering using legacy BIOS. However some experiences I had today are making me wonder about that.

I was experimenting with boot media...both USB thumb drives with various images, plus booting from physical CDs using an external USB burner I have (the new machine has no DVD/CD drive). When I switched the "Compatibility Support Module" settings in the setup to use legacy only, the horrific crap I saw happen was the most random, buggy stuff I've ever witnessed...almost can't even describe it. I even had USB keyboard lockups that required hitting the reset button...unimaginable. This is an ASrock X570 Phantom Gaming 4 motherboard with very recent firmware too, which should be really solid. No clue what that nightmare was all about. That pretty well scared me off of the legacy BIOS idea though I'm not sure what to think. The questions I have are:

1. Is anyone there using legacy BIOS for their Gentoo-only AMD machines?, and

2. Is anyone doing so with syslinux?

I see that EFI is clearly supported for syslinux:

https://wiki.gentoo.org/wiki/Syslinux#Setup_on_EFI_systems

Thanks in advance!
Tom

figueroa · Posted: Thu Dec 24, 2020 3:22 am Post subject:

Legacy BIOS goodness, or not, depends entirely on your particular BIOS. My older AMD machines don't even have EFI baloney. But every EFI I've worked with is buggy in many different respect. But, my primary desktop is an HP Pavillion HPE that boots in legacy mode only, and I use GRUB, but it's not AMD.

I've only used syslinux on my old Libretto Pentium 1 mini palmtop.

You don't have to let GRUB autogenerate the grub.cfg. You can roll your own.

Apparently your firmware isn't so solid, or there is operator error somewhere.
_________________
Andy Figueroa
hp pavilion hpe h8-1260t/2AB5; spinning rust x3
i7-2600 @ 3.40GHz; 16 gb; Radeon HD 7570
amd64/23.0/split-usr/desktop (stable), OpenRC, -systemd -pulseaudio -uefi

Tony0945 · Posted: Thu Dec 24, 2020 4:22 am Post subject:

Two AMD's, a Bulldozer and a Ryzen 2700X running rEFInd. Set it and forget it. No re-installing every time you rebuild a kernel. My first install was on the Bulldozer and I made some mistakes. The Ryzen went smoother. I didn't even have to use efibootmgr because of the excellent MSI BIOS. After installing via ebuild, I booted into the BIOS and saw the choice there and just used the BIOS to select it as the default boot. And don't put your kernels in the efi partition. Not needed, rEFInd will find them on an ext4 partition. No need for separate /boot either.

Strange spelling of REFInd is because that's how upstream spells it. The ebuild is refind.

Have zero experience with AsRock. I'm told is an el cheapo manufacturer.

Goverp · Advocate Joined: 07 Mar 2007 Posts: 2203

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Thanks for all the replies! I'm a bit confused because my total unfamiliarity with EFI.

saellaven · l33t Joined: 23 Jul 2006 Posts: 655

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Anon-E-moose · Posted: Thu Dec 24, 2020 4:41 pm Post subject:

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Thanks!

Tom

GDH-gentoo · Posted: Thu Dec 24, 2020 4:53 pm Post subject:

Tony0945 · Posted: Thu Dec 24, 2020 5:32 pm Post subject:

Here is the layout on my MSI 2700x board

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

saellaven · l33t Joined: 23 Jul 2006 Posts: 655

I have 32GB of RAM with a 32GB swap partition, mostly because I compile on tmpfs with 16 threads... even then, it barely ever swaps.

My original EFI install only had a 100 MB partition, but when I put my new systems together, I made it 1 GB... storage is cheap and I like having plenty of spare kernels around just in case something breaks. And all of my /boot is my FAT32 partition, I don't do a separate /boot and /boot/EFI.
_________________
Ryzen 3700X, Asus Prime X570-Pro, 64 GB DDR4 3200, GeForce GTX 1660 Super
openrc-0.17, ~vanilla-sources, ~nvidia-drivers, ~gcc

Tony0945 · Posted: Thu Dec 24, 2020 8:24 pm Post subject:

saellaven · l33t Joined: 23 Jul 2006 Posts: 655

Tony0945 · Posted: Fri Dec 25, 2020 2:16 am Post subject:

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Tony0945 · Posted: Fri Dec 25, 2020 3:40 pm Post subject:

tld, I do copy the kernels to /boot
I build with a sctipt. Someone much more adept than I could probably have the script adjust grub. IIRC, that's what genkernel does or did.
Here's my script:

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

saellaven · l33t Joined: 23 Jul 2006 Posts: 655

I have a separate script for building my kernel, which then calls this script to install it.

You'll note I install the current kernel twice. rEFInd always defaults to linux-current.efi on my system, but I have all of my previous kernels available too, in case of emergency breakage (which actually happened a couple months ago).

I also store a copy of the kernel's .config in /root/kernel so I have an archive of those as well

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Thanks everyone for the help, and thanks Tony0945 for the refind suggestion...I absolutely love that so far!

I was a little confused as to what I actually wanted in my /boot/refind_linux.conf. The default created by the refind-install was clearly not what I wanted (which is apparently expected when booted from the minimal install). I ended up with just this, which seems to work:

Tony0945 · Posted: Mon Dec 28, 2020 1:57 am Post subject:

tld · Veteran Joined: 09 Dec 2003 Posts: 1852

Interesting. Thanks for that. The entry I have now does seem to work. As far as the net.ifnames=0, so far I've never needed that. I have a dummy file at /etc/udev/rules.d/80-net-name-slot.rules to force the ethN format names. Unless I'm mistaken, the MAC address of the onboard Ethernet wold never change correct?...and as a result that should remain as eth0?

Thanks for all the help! I actually just got X running on the new machine and working correctly with the amdgpu stuff as far as I can tell...getting there.

Tom

Tony0945 · Posted: Mon Dec 28, 2020 2:58 pm Post subject:

A short divergence into persistent names. "net.ifnames=0" is a kernel command. Having a blank udev rule is a udev convention. I think there is a higher likelihood of udev changing it's convention than the kernel changing without notice. If you rely on udev, then one day you might do a portage update, reboot and find you can't get to the internet. Even if the liikelihood of changing without warning is the same, I update portage every week. I update the kernel roughly monthly (when a new kernel becomes stable) and I always keep at least one old kernel handy. I can either select that at boot or run "touch" and the old becomes the new and thus refind's default.

YMMV. It's Gentoo. Your box, your way.

BTW, I use the kernel line AND a blank udev file. I do have a box with on-board and PCI board NIC's. No "net.ifnames at boot" and two udev rules by MAC, naming them "lan0" and "lan1". I could have used nic0 and nic1 or maybe obnic0 and pcinic0. And possibly obeth0 and pcieth0. I do know that ETH0 is the same as eth0. The kernel will display uppercase names but somewhere inside it ignores case.

figueroa · Posted: Mon Dec 28, 2020 5:39 pm Post subject:

I've been getting along keeping my eth0 for many years with just: