stand: Improve common "boot" command

[kevans]

Summary

The common boot command claims to be able to take an explicit kernel to boot. If one specifies "boot kernel.GENERIC", boot will attempt to load a module named "kernel.GENERIC." The common case tends to be that a directory in /boot is named "kernel.GENERIC" with a "kernel" binary inside and this command will fail because it is not searching it.

Re-work it a little bit, fallback to try prepending /boot/$kernel to module_path and loading the "common_bootfiles" (i.e. kernel). This still doesn't quite match the functionality of the "boot" that forth seems to install because it doesn't load modules, but it at least allows the expected "boot $kernelname" to work.

[kevans]

Instead of doing arithmetic on argc, argv in try_kernel, just pass in the argc/argv that we're expecting to be passed to mod_loadkld.

[imp]

I'd honestly feel better if we did this in Lua instead.

[imp]

stand/common/boot.c

53

This gets used uninitialized if we take the first rv == 0 path.

74–75

we have asprintf, I thought, in libstand which would simplify this.

96

This test isn't needed. libsa's free copes with NULL. See bigger issue above.

[imp]

stand/common/boot.c

53

actually, it doesn't n/m.

[kevans]

Abandon ship, this is a bad idea.