eudev: specified group 'sgx' unknown

[ken@…]

I'm not sure quite what triggers this, but I have various reports in /var/log/syslog of the form:

udevd[203]: specified group 'sgx' unknown

I first noticed this while building BLFS in a tty after I'd used my kvm switch to come back to the machine and saw this on the tty. Now that I've been running a desktop I've got one such entry in the log from a bit over 5 hours ago but that was not at a time when I changed the KVM to or from another machine - there are various usb messages when I do that. My point is that I'm not sure if I can test that the fix will work ;-) However, we clearly do not have the group and have no need of it.

In systemd we change the render group to video and blank out the sgx group in 50-udev-default.rules.in. In sysv we do neither, but only sgx is being reported.

/me looks at eudev and systemd:

In systemd the file is rules.d/50-udev-default.rules.in but in eudev it is rules/50-udev-default.rules and only the systemd version mentions GROUP="render".

So, not quite the same sed for eudev.

[ken@…]

Fixed 507bf71541 pushed as part of r11.3-98.

[Bruce Dubbs]

I took a look at the eudev source and the only place I see 'sgx' is:

rules/50-udev-default.rules:SUBSYSTEM=="misc", KERNEL=="sgx_enclave", GROUP="sgx", MODE="0660"
rules/50-udev-default.rules:SUBSYSTEM=="misc", KERNEL=="sgx_vepc", GROUP="sgx", MODE="0660"

I do not know when or why the sgx_enclave or sgx_vepc are used.

Checking the kernel documentation:

The support can be determined by grep sgx /proc/cpuinfo. I do not have that in either my Intel Workstation or AMD development system. Perhaps that is because my kernel configurations have # CONFIG_X86_SGX is not set.

The kernel configuration says X86_SGX Depends on: X86_64 [=y] && CPU_SUP_INTEL [=y] && X86_X2APIC [=y]...

CONFIG_X86_X2APIC: If you don't know what to do here, say N.

CONFIG_X86_SGX: If unsure, say N.

[pierre]

We tell to enable CONFIG_X86_X2APIC on the LFS kernel page...

[ken@…]

SGX is described at ​https://www.kernel.org/doc/html/next/x86/sgx.html.

A perhaps more detailed description is at ​https://gramine.readthedocs.io/en/stable/sgx-intro.html - AFAICS you need special hardware (high-end intel servers, I think)

[Xi Ruoyao]

Replying to pierre:

We tell to enable CONFIG_X86_X2APIC on the LFS kernel page...

Intel says to enable it.

And AFAIK some "if unsure select Y/N" things in kernel configuration help entries are completely outdated.

[Bruce Dubbs]

Milestone renamed