On 2025-01-28 06:23, Milan Obuch wrote:
On Mon, 27 Jan 2025 19:28:28 +0100
Yamagi <li...@yamagi.org> wrote:
Hi,
sounds like the Alder Lakes PCID bug in N100 flavor. On the small
cores the INVLPG instruction is broken, failing to flush all
(global?) TLP entries leading to cache corruption. FreeBSD has a work
around for
that:
https://cgit.freebsd.org/src/commit/?id=cde70e312c3fde5b37a29be1dacb7fde9a45b94a
However that work around never fully solved the problem on the N100
series. My own N100 board was never stable with PCID enabled and
there are several other reports of the same problems. For example
https://lists.freebsd.org/archives/freebsd-current/2023-August/004116.html
Since Linux went with disabling PCID all together on all Alder Lake
and Raptor LAKE CPUs, I did the same by setting
vm.pmap.pcid_enabled=0 in loader.conf. Since I did that the system is
running fine.
The Linux commit disabling PCID is here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ae8373a5add4ea39f032563cf12a02946d1e3546
A microcode update might also help. I didn't test the updates
released by Intel since early last year so I don't know for sure.
It looks like the right thing, in my case adding vm.pmap.pcid_enabled=0
to /boot/loader.conf helps. I consider this easier than installing port
for microcode update...
That being said, could someone add some more pro/cons for those two
approaches?
Additionally, I am using M.2 SATA drive at the moment. While NVMe drive
worked to some extent, if fsck was necessary for some reason, it was
unpleasant - some 'waiting for nvme reset' event occured, this led to
nvme drive detach, and the only way to fix it was unscrew the drive,
put it in USB-NVMe converter, do fsck via USB drive, then mount it back
into box... not acceptable.
I chose microcode but that was hard to do because I only have one nvme
slot and the installer panicked trying to install the package at the
final part of the install. I had to install onto an SD and then use
another FreeBSD install to do a pkg chroot install onto that temporary
media and then use that to boot with the firmware update and chroot
install the firmware and edit loader.conf on the nvme.
The microcode update fixed it for me. I inferred from reading that
enable PCID might have a performance advantage.
Ian
