Re: i486 emu in mainline?

From: Alan Cox (alan_at_redhat.com)
Date: 05/23/04

  • Next message: Wilfried v. Hulzen: "PROBLEM: SCSI failure resulting in kernel panic - also 2.6.6 kernel" 
    Date:	Sun, 23 May 2004 07:08:36 -0400
To: Willy Tarreau <willy@w.ods.org>

    On Sun, May 23, 2004 at 10:29:12AM +0200, Willy Tarreau wrote:
    > being emulated. I think it's already the case. He also said that I
    > didn't take care of the segment selectors (such as SS) which some
    > programs use perfectly legally (eg Wine). I don't know how to do
    > that.

    You have to parse all the valid header bytes (the opcode prefixes) that
    change segment, cause repeats and change sizes. DOSemu has a worked example
    of this particular set of horrors.

    > - why not include the CMOV emulation while we're at it ? There are so
    > many people using VIA EDEN chips who think it's i686 compatible that
    > they may get hit too. IIRC, the chip only executes CMOV on registers,
    > but very slowly (a few tens of cycles), while register to memory
    > accesses generate a trap.

    gcc generates a lot of cmov on i686 so many that people I've talked with
    on the compiler side also feel cmov emulation isnt useful. Newer Eden btw
    has cmov.

    > Other than that, I'm happy that someone found it useful, and happy too that
    > someone did the 2.6 port :-)

    Is there a reason btw it can't be done with LD_PRELOAD ?

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    • Re: i486 emu in mainline?
      ... but I don't use the segment base in the TSS nor ... IIRC, the chip only executes CMOV on registers, ... > on the compiler side also feel cmov emulation isnt useful. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)
    • Re: i486 emu in mainline?
      ... but I don't use the segment base in the TSS nor ... IIRC, the chip only executes CMOV on registers, ... > on the compiler side also feel cmov emulation isnt useful. ... send the line "unsubscribe linux-kernel" in ...
      (Linux-Kernel)