Coordinated boot synchronization and startup of information handling system subsystems

A method, of a management controller in an information handling system comprising a processor, a basic input/output system (BIOS), and a plurality of subsystems including a first subsystem communicatively coupled to the processor, wherein the management controller is communicatively coupled to the processor and the first subsystem and configured for out-of-band management of the information handling system, the method comprising:

• grouping each subsystem of the plurality of subsystems into one of one or more groups based on capabilities of the plurality of subsystems;
• detecting an alternating power cycle of the information handling system, wherein a boot process of the BIOS and a boot process of the first subsystem both begin in response to the alternating power cycle;
• instructing, responsive to detecting the alternating power cycle, the BIOS of the information handling system to pause its boot process prior to Peripheral Components Interconnect (PCI) enumeration of functions of the plurality of subsystems until at least one subsystem in each of the one or more groups has completely booted and initialized its PCI functions, wherein the at least one subsystem comprises a subsystem with one or more virtual PCI functions;
• and
• upon detecting completion of the boot process and initialization of PCI functions of at least one subsystem of each of the one or more groups, instructing the BIOS to unpause its boot process.

An article of manufacture comprising:

• a non-transitory computer-readable medium;
• and
• computer-executable instructions carried on the computer-readable medium, the instructions readable by a management controller of an information handling system comprising a processor, a basic input/output system (BIOS), and a plurality of subsystems including a first subsystem communicatively coupled to the processor, and the management controller communicatively coupled to the processor and the first subsystem and configured for out-of-band management of the information handling system, the instructions, when read and executed, for causing the management controller to:
• group each subsystem of the plurality of subsystems into one of one or more groups based on capabilities of the plurality of subsystems;
• detect an alternating power cycle of the information handling system, wherein a boot process of the BIOS and a boot process of the first subsystem both begin in response to the alternating power cycle;
• instruct, responsive to detecting the alternating power cycle, the BIOS to pause its boot process prior to enumeration of Peripheral Components Interconnect (PCI) functions of the plurality of subsystems until at least one subsystem in each of the one or more groups has completely booted and initialized its PCI functions, wherein the at least one subsystem comprises a subsystem with one or more virtual PCI functions;
• and
• upon detecting completion of the boot process and initialization of PCI functions of at least one subsystem of each of the one or more groups, instruct the BIOS to unpause its boot process.