Software > Firmware

Basic understanding of OPAL

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cchinicz:
Well, that makes sense. OSs can handle that through whatever drivers (maybe OPAL can be better characterized as a "standard" driver for OSs running on openpower). But anyway, any OS which has been compromised will continue to be compromised boot after boot, it's statefull. The OPAL seems to add some tier between the HW and the OS that is not present on x86 machines and I like it. When I started this thread I wanted to better understand OPAL functionality and architecture. Now it's much clear to me. Thank you.

cchinicz:
Something else which intrigues me is what is skiboot? I suppose it's a Linux kernel. I read OPAL is started as part of skiboot and continues to run after Petitboot has loaded the OS and exited. Skiboot running OPAL after the OS has started has a relatively small footprint, some 0.5GB on my system (not so small as Mirage, which runs with some 30MB of RAM). As I'm not a code guy, I have no clue and would appreciate any inputs about this also.

ClassicHasClass:
Skiboot is not a Linux kernel. Skiboot's most important component is OPAL. It is also responsible for setting up the PCIe Host Bridges (PHBs) and certain other kinds of midlevel initialization. Once this is done, it then starts a kernel stored in the BOOTKERNEL firmware partition, which is usually Skiroot/Petitboot.

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