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r0b0t

Member

From: /tmp

Registered: 2009-05-24

Posts: 510

[SOLVED] /proc/cmdline won't change no matter what

I'm trying to enable PCI passthrough, my motherboard supports VT-d , and seems enabled :

kern  :info  : [  +0.000002] ACPI: DMAR 0x000000003952A788 0000A8 (v01 ALASKA A M I    00000002      01000013)
kern  :info  : [  +0.000001] ACPI: Reserving DMAR table memory at [mem 0x3952a788-0x3952a82f]
kern  :info  : [  +0.000001] DMAR: Host address width 39
kern  :info  : [  +0.000001] DMAR: DRHD base: 0x000000fed90000 flags: 0x0
kern  :info  : [  +0.000003] DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap 1c0000c40660462 ecap 19e2ff0505e
kern  :info  : [  +0.000002] DMAR: DRHD base: 0x000000fed91000 flags: 0x1
kern  :info  : [  +0.000002] DMAR: dmar1: reg_base_addr fed91000 ver 1:0 cap d2008c40660462 ecap f050da
kern  :info  : [  +0.000001] DMAR: RMRR base: 0x000000399d4000 end: 0x00000039c1dfff
kern  :info  : [  +0.000001] DMAR: RMRR base: 0x0000003b000000 end: 0x0000003f7fffff
kern  :info  : [  +0.000001] DMAR-IR: IOAPIC id 2 under DRHD base  0xfed91000 IOMMU 1
kern  :info  : [  +0.000001] DMAR-IR: HPET id 0 under DRHD base 0xfed91000
kern  :info  : [  +0.000001] DMAR-IR: Queued invalidation will be enabled to support x2apic and Intr-remapping.
kern  :info  : [  +0.001540] DMAR-IR: Enabled IRQ remapping in x2apic mode
kern  :info  : [  +0.003745] iommu: Default domain type: Translated 
kern  :info  : [  +0.000001] AMD-Vi: AMD IOMMUv2 driver by Joerg Roedel <jroedel@suse.de>
kern  :info  : [  +0.000001] AMD-Vi: AMD IOMMUv2 functionality not available on this system

However the script does not show any groups.

#!/bin/bash
shopt -s nullglob
for g in `find /sys/kernel/iommu_groups/* -maxdepth 0 -type d | sort -V`; do
    echo "IOMMU Group ${g##*/}:"
    for d in $g/devices/*; do
        echo -e "\t$(lspci -nns ${d##*/})"
    done;
done;

IOMMU Group .:

I have tried setting :
1)

cat /etc/default/grub | grep iommu
GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 intel_iommu=on iommu=pt"

2)

cat /etc/default/grub | grep iommu
GRUB_CMDLINE_LINUX_DEFAULT="loglevel=3 intel_iommu=on quiet"

Always remembering to regenerate grub.cfg & reboot, I also verified always the vmlinuz lines :

cat /boot/grub/grub.cfg | grep vmlinuz
	linux	/boot/vmlinuz-linux root=UUID=1324209f-aa53-4ca0-be48-425ba67a84db rw cryptdevice=/dev/nvme0n1p2:cryptroot loglevel=3 intel_iommu=on iommu=pt
		linux	/boot/vmlinuz-linux root=UUID=1324209f-aa53-4ca0-be48-425ba67a84db rw cryptdevice=/dev/nvme0n1p2:cryptroot loglevel=3 intel_iommu=on iommu=pt
		linux	/boot/vmlinuz-linux root=UUID=1324209f-aa53-4ca0-be48-425ba67a84db rw cryptdevice=/dev/nvme0n1p2:cryptroot loglevel=3 intel_iommu=on iommu=pt

And they reflected /etc/default/grub changes accordingly...
*However* , /proc/cmdline always shows :

cat /proc/cmdline 
BOOT_IMAGE=/boot/vmlinuz-linux root=UUID=1324209f-aa53-4ca0-be48-425ba67a84db rw cryptdevice=/dev/nvme0n1p2:cryptroot loglevel=3 quiet

I don't have any weird modprobes , no blacklists.

Last edited by r0b0t (2021-09-18 03:27:38)

r0b0t

Member

From: /tmp

Registered: 2009-05-24

Posts: 510

Re: [SOLVED] /proc/cmdline won't change no matter what

Finally found what was wrong, somehow, for some reason there was no boot partition , and everything was encrypted, it seems that this encryption somehow messed up with the way the kernel booted so it didn't take any options into consideration.
Had to do a reinstall and by using a dedicated partition for boot / efi (as I should from the beginning) now it works.

solskog

Member

Registered: 2020-09-05

Posts: 462

Re: [SOLVED] /proc/cmdline won't change no matter what

Did you enable AMD-SVM on BIOS?

kern  :info  : [  +0.000001] AMD-Vi: AMD IOMMUv2 functionality not available on this system

r0b0t

Member

From: /tmp

Registered: 2009-05-24

Posts: 510

Re: [SOLVED] /proc/cmdline won't change no matter what

That's normal, it's not available because it's a mobo for Intel processors , so I have VT-d enabled.
So the problem was because my /boot was inside of an encrypted partition.