[PVE-User] Dell PowerEdge T140, megaraid, BIOS Boot...

[RolandK]

hello,

there is a note at https://pve.proxmox.com/wiki/Roadmap#Proxmox_VE_8.2


        Kernel: |intel_iommu| now defaults to on

The |intel_iommu| parameter defaults to |on| in the kernel 6.8 series. 
Enabling IOMMU can cause problems with older hardware, or systems with 
not up to date BIOS, due to bugs in the BIOS.

The issue can be fixed by explicitly disabling |intel_iommu| on the 
kernel commandline (|intel_iommu=off|) following the reference 
documentation 
<https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysboot_edit_kernel_cmdline>. 


does intel_iommu=off also help ?

regards
Roland

Am 02.05.25 um 17:21 schrieb Marco Gaiarin:
> I've just upgraded to PVE8 a little cluster built with an PowerEdge T340
> (boot in UEFI mode) and an T140 (boot in BIOS mode).
>
> T340 works like a charme; T140 after rebooting panicked because cannot find
> root filesystem; looking carefully at kernel log revealed that disks get not
> recognized, and going deeper lead me to:
>
>   gaio at leia:~$ grep megaraid T140_boot_log.txt
>   [   31.952470] megaraid_sas 0000:01:00.0: FW now in Ready state
>   [   31.952472] megaraid_sas 0000:01:00.0: 63 bit DMA mask and 32 bit consistent mask
>   [   31.952624] megaraid_sas 0000:01:00.0: firmware supports msix        : (96)
>   [   31.952750] megaraid_sas 0000:01:00.0: requested/available msix 5/5 poll_queue 0
>   [   31.952752] megaraid_sas 0000:01:00.0: current msix/online cpus      : (5/4)
>   [   31.952753] megaraid_sas 0000:01:00.0: RDPQ mode     : (disabled)
>   [   31.952758] megaraid_sas 0000:01:00.0: Current firmware supports maximum commands: 928        LDIO threshold: 237
>   [   31.954076] megaraid_sas 0000:01:00.0: Performance mode :Latency (latency index = 1)
>   [   31.954078] megaraid_sas 0000:01:00.0: FW supports sync cache        : No
>   [   31.954080] megaraid_sas 0000:01:00.0: megasas_disable_intr_fusion is called outbound_intr_mask:0x40000009
>   [   32.362294] megaraid_sas 0000:01:00.0: Ignore DCMD timeout: megasas_get_ctrl_info 5382
>   [   32.665126] megaraid_sas 0000:01:00.0: Could not get controller info. Fail from megasas_init_adapter_fusion 1907
>   [   32.908139] megaraid_sas 0000:01:00.0: Failed from megasas_init_fw 6539
>
> googling a bit lead me to some forum and pages; after some test i've added
> to kernel boot parameters:
>
> 	iommu=pt
>
> and now server boot flawlessy.
>
>
> The two servers have different hardware but share the same BIOS, so this
> lead to me to the hypotesis that the new megaraid_sas kernel driver depend
> on UEFI initialization to work, or something like this.
>
> Also, i've understood that 'pt' mean 'PassThrought', but i've not clear what
> overral consequences (performance, stability, ...) have this options.
>
>
> I'm seeking feedback. Thanks.
>