Problem:
Gen 4 capable CPU + board (H12SSL-NT), Gen 4 capable SSD (Samsung PM1733) connected to onboard SlimSAS (JNVMe0 / JNVMe1)
Gen 3 capable cable (CBL-SAST-0826) + backplane (BPN-SAS3-826A-N4)
CPU and SSD will negotiate to Gen 4. Results in lots of PCIe errors because cable + backplane are only Gen3 capable
The board H12SSL-NT does not have any option to force PCIe link speed (thanks for nothing, Supermicro :facepalm
Solution (for Proxmox 8.1-1)
Copy
Copy
If everything looks good:
Possible Improvements:
Execute even earlier, somewhere in initramfs
License:
pcie_set_speed.sh
PM1733_force_gen3.sh
PM1733_force_gen3.sh
Gen 4 capable CPU + board (H12SSL-NT), Gen 4 capable SSD (Samsung PM1733) connected to onboard SlimSAS (JNVMe0 / JNVMe1)
Gen 3 capable cable (CBL-SAST-0826) + backplane (BPN-SAS3-826A-N4)
CPU and SSD will negotiate to Gen 4. Results in lots of PCIe errors because cable + backplane are only Gen3 capable
The board H12SSL-NT does not have any option to force PCIe link speed (thanks for nothing, Supermicro :facepalm
Solution (for Proxmox 8.1-1)
Copy
pcie_set_speed.sh
and PM1733_force_gen3.sh
to /usr/local/sbin
Copy
PM1733-force-gen3.service
to /etc/systemd/system/PM1733-force-gen3.service
Code:
systemctl daemon-reload
systemctl start PM1733-force-gen3.service
journalctl -u PM1733-force-gen3.service
Code:
systemctl enable PM1733-force-gen3.service
Execute even earlier, somewhere in initramfs
License:
Code:
pcie_set_speed.sh by https://alexforencich.com/wiki/en/pcie/set-speed
Distributed under CC Attribution-Share Alike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)
Code:
#!/bin/bash
dev=$1
speed=$2
if [ -z "$dev" ]; then
echo "Error: no device specified"
exit 1
fi
if [ ! -e "/sys/bus/pci/devices/$dev" ]; then
dev="0000:$dev"
fi
if [ ! -e "/sys/bus/pci/devices/$dev" ]; then
echo "Error: device $dev not found"
exit 1
fi
pciec=$(setpci -s $dev CAP_EXP+02.W)
pt=$((("0x$pciec" & 0xF0) >> 4))
port=$(basename $(dirname $(readlink "/sys/bus/pci/devices/$dev")))
if (($pt == 0)) || (($pt == 1)) || (($pt == 5)); then
dev=$port
fi
lc=$(setpci -s $dev CAP_EXP+0c.L)
ls=$(setpci -s $dev CAP_EXP+12.W)
max_speed=$(("0x$lc" & 0xF))
echo "Link capabilities:" $lc
echo "Max link speed:" $max_speed
echo "Link status:" $ls
echo "Current link speed:" $(("0x$ls" & 0xF))
if [ -z "$speed" ]; then
speed=$max_speed
fi
if (($speed > $max_speed)); then
speed=$max_speed
fi
echo "Configuring $dev..."
lc2=$(setpci -s $dev CAP_EXP+30.L)
echo "Original link control 2:" $lc2
echo "Original link target speed:" $(("0x$lc2" & 0xF))
lc2n=$(printf "%08x" $((("0x$lc2" & 0xFFFFFFF0) | $speed)))
echo "New target link speed:" $speed
echo "New link control 2:" $lc2n
setpci -s $dev CAP_EXP+30.L=$lc2n
echo "Triggering link retraining..."
lc=$(setpci -s $dev CAP_EXP+10.L)
echo "Original link control:" $lc
lcn=$(printf "%08x" $(("0x$lc" | 0x20)))
echo "New link control:" $lcn
setpci -s $dev CAP_EXP+10.L=$lcn
sleep 0.1
ls=$(setpci -s $dev CAP_EXP+12.W)
echo "Link status:" $ls
echo "Current link speed:" $(("0x$ls" & 0xF))
Code:
#!/bin/sh
set -o errexit # abort on nonzero exitstatus
set -o nounset # abort on unbound variable
lspci | grep "PM173X" | cut -d ' ' -f1 | while read line; do
echo "Forcing PM173X at $line to Gen3 Link Speed"
./pcie_set_speed.sh "$line" 3
echo ""
done
Code:
[Unit]
Description=Force PM1733 SSDs to Gen3 Speed
# Run as early as possible
Before=basic.target
After=local-fs.target sysinit.target
DefaultDependencies=no
[Service]
Type=oneshot
ExecStart=PM1733_force_gen3.sh
WorkingDirectory=/usr/local/sbin
[Install]
WantedBy=basic.target