[SOLVED] IBT Support (default since kernel 6.2)

[marmel]

I chimed in on Ticket #21435
https://www.virtualbox.org/ticket/21435

... with the same comment/question as below. Seems these forums are more actively supported than the bug tracker, as there's zero developer response to the many of the tickets I follow since Vbox 7.x was released:
viewtopic.php?f=7&t=108440&p=532943

After having waited nearly a year since the kernel 5.18 release introduced IBT (May 2022), for nVidia to get their act together and support IBT in their proprietary modules (530.41.03 finally!), I now come to realize that the latest Virtualbox 7.0.6 fails with IBT enabled.

This has been the default config as of kernel 6.2.x. Currently running 6.2.7 here.

Workaround: Add ibt=off kernel parameter

[scottgus1]

No ideas about the IBT thing here, but on this:

there's zero developer response to the many of the tickets I follow since Vbox 7.x was released:

This is common, The devs often go off to fix the bugs based on the data without necessarily posting back on the tickets. And 7.0 is a big dev push just now. Some of the tickets are specific requests to get data to figure out the graphics bugs in 7.0.

[scottgus1]

As a possible workaround, your link to the Arch wiki here viewtopic.php?f=7&t=108892&p=534175#p534173 says:

you can try adding ibt=off as a kernel parameter.

[marmel]

As a possible workaround, your link to the Arch wiki here viewtopic.php?f=7&t=108892&p=534175#p534173 says:

you can try adding ibt=off as a kernel parameter.

I think you may have replied to the wrong thread, but thanks. I provided that link to the workaround here for another user:
viewtopic.php?f=7&t=108892#p534173

EDIT: Perhaps it wasn't clear (only implied) from my OP that those of us using the nVidia proprietary driver have been applying the ibt=off kernel parameter for about a year now, until the recently released nVidia driver arrived, which was compiled with support for IBT.

[marmel]

Virtualbox 7.0.8 also fails to launch with IBT enabled (the default kernel config).

System journal errors are consistent with kernel modules being built without support for Indirect Branch Tracking.

Code: Select all

May 20 08:50:12 kernel: traps: Missing ENDBR: 0xffffa99507f4a430
May 20 08:50:12 kernel: kernel BUG at arch/x86/kernel/traps.c:255!
May 20 08:50:12 kernel: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI

This has been the default kernel config on Arch Linux for 14 months now, and will soon be the default in Debian, Ubuntu, etc.

Bug ticket updated thusly:
https://www.virtualbox.org/ticket/21435

[marmel]

Linking another forum thread where lack of IBT support in recent Virtualbox releases (7.0.8 at time of post) turned out to be the culprit:

• viewtopic.php?t=109458

Looks like Fedora users are starting to hit this issue now as well.

[marmel]

And another thread on this issue (Fedora):

• viewtopic.php?t=109439

Workaround: Add ibt=off kernel parameter

[marmel]

Yet another thread, same issue (openSUSE):

• viewtopic.php?t=109488

Workaround: Add ibt=off kernel parameter

[marmel]

Mods: Perhaps consider pinning this thread until VB supports compiling kernel modules with IBT support?

@scottgus1
@mpack

[scottgus1]

@Marmel, I asked our forum Linux gurus to investigate the possibility of an IBT sticky, we'll see what we can do!

[marmel]

@Marmel, I asked our forum Linux gurus to investigate the possibility of an IBT sticky, we'll see what we can do!

Great, thanks! I think it might be helpful.

We Arch folks went through this last year when the IBT switch was toggled on in the kernel config. There were many, many threads all with the same solution. nVidia driver users (myself included) could not boot to a graphical desktop with IBT enabled.

[marmel]

Linking another new Fedora thread where IBT was the issue:

• viewtopic.php?t=109509

Workaround: Add ibt=off kernel parameter

[marmel]

Another new openSUSE Tumbleweed thread where IBT was the issue:

• viewtopic.php?t=109587

Workaround: Add ibt=off kernel parameter

[scottgus1]

Marmel, would you happen to know how to test if a Linux host has IBT enabled, and what command & output a user might see?

I have a sticky ready to go but I need that info to complete it.

[fth0]

The following command inside a Linux terminal could give the following output if IBT is supported by the running Linux kernel (at least on Debian Linux / Ubuntu Linux / Linux Mint):

Code: Select all

grep X86_KERNEL_IBT /boot/config-$(uname -r)
CONFIG_X86_KERNEL_IBT=y