Add IPMI OEM command LinuxBootDone

Add a new OEM command for LinuxBoot to notify the BMC when it is about
to kexec into the OS. This is intended to give the BMC a chance to
prepare for an untrusted OS, e.g. disable any interfaces it doesn't want
the OS to have access to.

Tested:
Exercised the new OEM command using ipmitool
$ ipmitool raw 0x2e 0x32 0x79 0x2b 0x00 0x11
  79 2b 00 11

Change-Id: Ica76d77cdde48cebfbced32d8e7e860b559074e8
Signed-off-by: John Wedig <johnwedig@google.com>
diff --git a/handler.hpp b/handler.hpp
index 3b0a372..16b8208 100644
--- a/handler.hpp
+++ b/handler.hpp
@@ -203,6 +203,14 @@
      * @return list of lanes taken by each device.
      */
     virtual std::vector<uint8_t> pcieBifurcation(uint8_t index) = 0;
+
+    /**
+     * Prepare for OS boot.
+     *
+     * If in bare metal mode, the BMC will disable IPMI, to protect against an
+     * untrusted OS.
+     */
+    virtual void linuxBootDone() const = 0;
 };
 
 } // namespace ipmi