grub2 always adds "memtest86 serial console" even when no serial port

Bug #567955 reported by tz on 2010-04-21
This bug affects 6 people
Affects Status Importance Assigned to Milestone
memtest86+ (Ubuntu)

Bug Description

Binary package hint: grub2

I have a laptop that does not and will never have an ordinary serial port.

Yet grub2 insists on adding the memory test for serial console that WILL NEVER WORK!.

There appears to be no way to disable this.

For some reason nodes are created in /dev for ttyS0 through ttyS3, but there is no underlying device. stty will return error, as will "cat". They are like a hanging symlink.

h1repp (heinz-repp) wrote :

confirming - a newly installed Lucid Netbook Edition to my Asus EeePC 1000h added a memtest serial (115000 bps) boot option to the boot menu - pretty useless.

Changed in grub2 (Ubuntu):
status: New → Confirmed
Colin Watson (cjwatson) wrote :

Quite true, but the memtest86+ package controls this, so reassigning.

Changed in grub2 (Ubuntu):
importance: Undecided → Medium
status: Confirmed → Triaged
affects: grub2 (Ubuntu) → memtest86+ (Ubuntu)
tags: added: iso-testing

Actually, you likely do have hardware for the serial ports. It's part of the legacy ISA stuff in your north bridge.
Just your laptop does not have the pins hooked up to a DB9. My laptop's docking station exposes those.

What I think is that memtest86 should look for console= in the kernel config file, and not add the serial console unless
kernel has one.

tz (thomas-mich) wrote :

No, my netbook has nothing at the corresponding ports or interrupt vectors.

But to expand on your point, few have the special hardware to connect a serial console, so this shold be off unless someone has the knowledge to turn it on

The Loeki (the-loeki) wrote :

As a related comment, the serial port is *always* ttyS0, even when it's not there, and even when both GRUB2 itself and the kernel are all configured to go to, say ttyS1 or something completely else.

I propose to modify /etc/grub.d/20_memtest86+

* Look at /sys/class/tty/ ; if there's nothing in there that's not virtual (there should be a good way to weed out the virtual devices by looking at this), skip the serial port config
* AND/OR look at GRUB2/the kernel; if they're not configured for serial communication, why should you for memtest?

Changed in memtest86+:
status: Unknown → New
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