Finally upgraded Proxmox based 6.2 install to 7.0-41222. It took me good 3-4 hours to figure out how the new boot loader works, so hopefully information bellow will help others:
1. I am using LSI SAS 2008 flashed in IT mode to passthrough HDDs (4x4TB)
2. Also passing 82579LM ethernet card for dedicated network.
3. Booting VM from USB (couldn't get SATA boot to work properly).
4. Used this repo to build loader with mptsas and mpt2sas drivers
5. bromolow_user_config.json
{
"extra_cmdline": {
"pid": "0x6387",
"vid": "0x058f",
"sn": "xxxxxx",
"mac1": "xxxxxxx",
"netif_num": 1,
"DiskIdxMap": "0C",
"SataPortMap": "1",
"SasIdxMap": "0"
},
"synoinfo": {},
"ramdisk_copy": {},
"extensions": []
}
PS. I have RS18017xs+ and DS1817+ for production. This VM used for backup and test purposes.