Reads, under macOS, the keys the Vinix SMC driver uses from the SMC of the Mac it runs on: whether each key is there, its four-character type, its size, its attribute bits, and its bytes in the order the SMC holds them.

tools/apple-smc/smcprobe              # the keys kernel/apple/smc reads
tools/apple-smc/smcprobe B0RM TB0T    # these keys
tools/apple-smc/smcprobe --all        # every key the SMC lists

It needs a V compiler (found as for every other tool, through build-support/find-v.sh) and the command line tools of Xcode. It runs as an ordinary user and only reads: through the AppleSMC user client it sends the commands that describe a key, read a key and name the key with a given number, and it has no code that writes one.

The driver takes a key for what Linux's drivers say it is, and reads it with the size the SMC itself gives for it (M1 battery). Before the driver is trusted on a machine it has never run on, this says what that machine's SMC has, from the system that is known to work on it:

• a key the driver wants that is absent will have no file in /sys;
• a key whose size is not the one in the table of docs/m1-battery.md is left out by the driver (keys_odd_sized in /sys/devices/platform/apple-smc/smc/status counts them), and that is worth knowing before booting;
• BCF0 of one byte means the remaining charge B0RM is little-endian, of four bytes that it is big-endian: compare B0RM both ways with B0FC.

Once Vinix runs on the machine, /sys/devices/platform/apple-smc/smc/keys lists the same thing as the driver saw it, one key type size attributes line each, to be laid beside this tool's output.

A MacBook Pro Mac17,6 (M5 Max) under macOS 26.5 (25F71), 2026-10-11. This is not the machine the driver is for; it confirms types, sizes and byte orders, not which keys an M1 has.

Of the 3668 keys this SMC lists, 361 begin with T: 344 are flt , 9 are ioft (48.16 fixed point, little-endian: TG0B read 33b3220000000000, 34.70 degrees) and 8 are si32. None is sp78.