Finding candidates to replace their microcode

By: Rick C. Hodgin (rickh.delete@this.geek.com), August 21, 2004 4:58 am
Room: Moderated Discussions
>So IMO it didn't make sense 30 years ago and it makes
>even less sense today.

I would like to see a range of instructions which are application- or task-specific. The physical instruction opcodes do not execute, but rather instruct the processor to draw opcodes from a cached area of code (stored in the TSS, for example) which then executes previously stored instruction sequences as though they were a single instruction.

This would allow single ops to have the effect of several concatenated instructions. And, since the code would always come from TSS, it would utilize whatever caching mechanisms exist for storing the TSS before/during/after task switching, subsequently polluting the cache less by having less code to execute, and provide a way to produce code which is globally dynamic (by changing the opcodes stored in TSS at one location, you change their functionality for the entire application or task).

Eleven opcode sequences, 0x0f;0c through 0x0f;0f, and 0x0f;19 through 0x0f;1f, are currently free (unless my IA-32 Revision 2.0 manual is out of date). The instructions could be called COPA through COPK for Custom OPeration A through K.

I can think of a multitude of really beneficial uses for such an ability.

- Rick C. Hodgin
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Opteron Exposed: Reverse Engineering AMD K8 Microcode UpdatesAnonymous2004/07/22 01:39 AM
  Opteron Exposed: Reverse Engineering AMD K8 MicrocDresdenboy2004/07/22 05:13 AM
    Opteron Exposed: Reverse Engineering AMD K8 MicrocAK2004/07/22 08:49 AM
      Opteron Exposed: Reverse Engineering AMD K8 MicrocDresdenboy2004/07/22 10:26 AM
        the former posting has no new text, continue hereDresdenboy2004/07/22 10:32 AM
  An additionDresdenboy2004/07/22 08:04 AM
    An additionAnonymous2004/07/22 02:32 PM
      An additionDresdenboy2004/07/22 02:55 PM
  Opteron Exposed: Reverse Engineering AMD K8 Microctom vier2004/07/22 08:38 AM
    Opteron Exposed: Reverse Engineering AMD K8 MicrocWouter Tinus2004/07/22 08:56 AM
    Opteron Exposed: Reverse Engineering AMD K8 MicrocIgor2004/07/23 10:00 PM
      Opteron Exposed: Reverse Engineering AMD K8 MicrocKronos2004/07/24 02:04 PM
  Opteron Exposed: Reverse Engineering AMD K8 Microcode UpdatesMax2004/07/22 01:01 PM
    Opteron Exposed: Reverse Engineering AMD K8 Microcode UpdatesAnonymous2004/07/22 05:26 PM
  Does that means..._Arthur2004/07/22 10:01 PM
    Does that means...Dresdenboy2004/07/23 03:27 AM
    Does that means...Jan2004/07/23 07:51 AM
      Does that means...Anonymous2004/07/23 03:10 PM
        Does that means...Igor2004/07/23 10:42 PM
          Does that means...Anonymous2004/07/24 09:53 PM
            Does that means...Igor2004/07/25 12:08 AM
            Does that means...Anonymous2004/07/25 12:17 AM
              Does that means...anonymous2004/07/25 04:31 PM
                Does that means...Igor2004/07/26 08:42 PM
  Permanent virusess.chauhan2004/07/27 12:25 AM
    Permanent virusesAnonymous2004/07/27 10:42 AM
  Finding candidates to replace their microcodeDresdenboy2004/08/19 02:06 AM
    Finding candidates to replace their microcodePaul DeMone2004/08/19 06:22 AM
      Finding candidates to replace their microcodeDavid Kanter2004/08/19 06:53 AM
        Finding candidates to replace their microcodefoobar2004/08/19 09:55 AM
          Finding candidates to replace their microcodeDavid Kanter2004/08/19 10:58 AM
          Finding candidates to replace their microcodeAnonymous2004/08/20 01:56 PM
            Finding candidates to replace their microcodehobold2004/08/23 03:14 PM
      Finding candidates to replace their microcodeDresdenboy2004/08/19 10:59 AM
        Finding candidates to replace their microcodeanonymous2004/08/19 03:35 PM
        Finding candidates to replace their microcodeAnonymous2004/08/20 02:23 PM
          Finding candidates to replace their microcodeGroo2004/08/20 09:25 PM
          Finding candidates to replace their microcodeDresdenboy2004/08/21 05:01 AM
            Finding candidates to replace their microcodeAnonymous2004/08/21 04:45 PM
              Finding candidates to replace their microcodeanonymous2004/08/21 09:45 PM
      Finding candidates to replace their microcodeMatt Craighead2004/08/19 01:18 PM
      Finding candidates to replace their microcodeRick C. Hodgin2004/08/21 04:58 AM
        Finding candidates to replace their microcodeanonymous2004/08/21 09:41 PM
          Finding candidates to replace their microcodeRick C. Hodgin2004/08/22 08:31 AM
            Finding candidates to replace their microcodeanonymous2004/08/23 08:56 AM
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