Am 20.01.2016 um 18:09 schrieb Maurizio Vitale:
As for modifying the instruction set of an Intel processor, I don't know how feasible it is.
Some CPUs allowed this. There were even designs that had PL/1 instructions implemented as assembly by way of microcode. In theory it's possible for newer Intel CPUs. One point against doing so is that the microcode updates are 2-8 kBytes in size. You'd need to switch microcode with every context switch in the operating system. The other point is that microcode updates are encrypted and signed. Only Intel has the private keys needed to provide data so that an Intel CPU will accept a microcode update (this is supposed to prevent tampering with the microcode update data by malicious third parties). Sources: http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32... pp. 338 ff. has infos about the general format of an update. http://www.delidded.com/how-to-update-cpu-microcode-in-award-or-phoenix-bios... lists typical microcode update sizes near the end (not sure whether these are in bytes or in DWORDs). Regards, Jo