[Crash-utility] Re: [RFC] Provide minimal debugging to crash

I haven't walked through all the restricted command list code paths to verify that they can work properly for all architectures without, say, kernel_init(), the 3 machdep_init() calls, vm_init() etc. having run. Certainly trying to rd or dis vmalloc addresses would display garbage data or just fail, but that's to be expected. I quickly tried this on a x86 and x86_64 -- but have you tried this on an ia64 or ppc64?

The only thing I'm not excited about is all the re-tinkering with the help screen output. Why bother? I'd prefer to keep things simple. During initialization, display a WARNING message that lists the supported commands just prior to the first prompt. And then just leave the help screen alone, and let your command-restriction mechanism display the per-command message: error(INFO, "command: %s not available in minimal mode\n", args[0]); ...and then perhaps followed up immediately with the acceptable command list again.

Another minor suggestion -- I think you can put the "eval" command in the supported list. I use it all the time, and in this minimal environment it may come in very handy. (There may be others, but they're probably not worth having...)