This reduces the amount of noise in the Linux kernel config files
by only storing the differences from the stock configuration.
It adds a new makefile target 'linux.saveconfig' to convert the
build tree's .config file into config/linux-linuxboot.config.
The Librem Key is a custom device USB-based security token Nitrokey is
producing for Purism and among other things it has custom firmware
created for use with Heads. In particular, when a board is configured
with CONFIG_LIBREMKEY, this custom firmware allows Heads to use the
sealed TOTP secret to also send an HOTP authentication to the Librem
Key. If the HOTP code is successful, the Librem Key will blink a green
LED, if unsuccessful it will blink red, thereby informing the user that
Heads has been tampered with without requiring them to use a phone to
validate the TOTP secret.
Heads will still use and show the TOTP secret, in case the user wants to
validate both codes (in case the Librem Key was lost or is no longer
trusted). It will also show the result of the HOTP verification (but not
the code itself), even though the user should trust only what the Librem
Key displays, so the user can confirm that both the device and Heads are
in sync. If HOTP is enabled, Heads will maintain a new TPM counter
separate from the Heads TPM counter that will increment each time HOTP
codes are checked.
This change also modifies the routines that update TOTP so that if
the Librem Key executables are present it will also update HOTP codes
and synchronize them with a Librem Key.
This modifies the segment at 0x0 so that it contains enough of a fake
Extended BIOS Data Area at addresses 0x40e and 0x413 that Xen can
correctly locate its trampoline code.
Since custom Xen is no longer required, we can remove the module,
the patches and all of the references to it in the board definition
files.
The modules file had a few errors that prevented slang from being built.
First the src/elfobjs file needed to be created before make started.
Second it needed to be configured without external png, pcre and onig
libraries it doesn't need for this application.
