RE: [PATCH 1/1] x86: add "udb" opcode (permanent official #UD in 64-bit mode)

[H. Peter Anvin]

On August 11, 2025 7:15:52 PM PDT, "Jiang, Haochen" <haochen.jiang@intel.com> wrote:
>> From: H.J. Lu <hjl.tools@gmail.com>
>> Sent: Tuesday, August 12, 2025 2:31 AM
>> 
>> On Mon, Aug 11, 2025 at 10:48 AM H. Peter Anvin <hpa@zytor.com> wrote:
>> >
>> > The opcode D6 has been officially reserved as a single-byte permanent
>> > undefined (#UD) opcode in 64-bit mode with the mnemonic UDB.  This is
>> > already the behavior of all known 64-bit implementations; this is thus
>> > merely an official statement of forward compatibility and the
>> > assignment of a mnemonic.
>> >
>> > This will be documented in the next version of the Intel Software
>> > Developer's Manual; in the meantime I DO speak officially for Intel on
>
>If you do think we need to hurry this patch in before next SDM published,
>which should happen at the end of September, please make sure you add
>this into the patch note since it is not released yet.
>
>Thx,
>Haochen
>
>> > this issue.
>> >
>> > The x86 Advisory Council has ratified this decision, and so it is
>> > expected to be honored across vendors, but I obviously cannot make any
>> > official statement on any other vendor's behalf.
>> >
>> > I am covered by the Intel-FSF copyright assignment for binutils.
>> >
>> > Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
>
>

Didn't I do exactly that?