Mellanox FlexBoot hangs system startup

On all boots, the MCX313A-BCBT 40GbE adapter brings up the Mellanox FlexBoot screen. However on some occasions, it hangs and does not let the boot process continue.

In such a case, it prints:

Mellanox FlexBoot v3.4.521

iPXE ( ) 0A:00.0 003E PCI3.00 PnP PMM+_

…and then it just stops until a power cycle.

Any ideas why?


at this point in the boot process I cannot make a screenshot yet, so attached is a photo.

Normally, the sequence is like Mellanox Flexboot inits, Integrated Ethernet boot ROM1 inits, Integrated Ethernet boot ROM2 inits, then comes the AMI BIOS screen, and then it starts booting the first boot device.

Please note that the Mellanox card is not used for PXE, as in this specific case we have been booting from a local SSD drive. Therefore none of the PXE entries have been activated.

Nevertheless, this message appears first during the whole boot process.

When it hangs, it does so at this point:

Please note that I have tried to disable this (as we do not need it) from:

-the FlexBoot configuration (set Option ROM → Disabled)

-using “flint -dev drom” → this did not succeed.

Then, on the official support site, I have been advised to use

flint -d --allow_rom_change drom

instead, which apparently removed the ROM and the message altogether. This avoids the problem in my case, but I guess it should not stop there anyway.

Best regards,


Hello Peter,

Can you please attach a screenshot?

Also can you please tell whether the Mellanox HCA is enabled on the pxe boot sequence?



Hi Peter,

Thank you for the screenshot, it indicated the phase when Mellanox HCA is declaring about its PXE but its not the boot process.

Please check the boot settings on BIOS and set the Mellanox HCA to be part of the boot process, maybe even the first boot option.