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Re: [committed, PATCH] PR binutis/18386: callw with 0x66 prefix incorrectly disassembled in 64-bit mode
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Jan Beulich <JBeulich at suse dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Mon, 11 May 2015 04:04:46 -0700
- Subject: Re: [committed, PATCH] PR binutis/18386: callw with 0x66 prefix incorrectly disassembled in 64-bit mode
- Authentication-results: sourceware.org; auth=none
- References: <20150509135213 dot GA720 at gmail dot com> <555076520200007800078B8F at mail dot emea dot novell dot com>
On Mon, May 11, 2015 at 12:28 AM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 09.05.15 at 15:52, <email@example.com> wrote:
>> The operand size prefix (0x66) is ignored for 32-bit PC-relative call,
>> jmp and jcc in 64-bit mode.
> Now that's again a change that should have been discussed
> before committing: While it is correct for the Intel implementation
> of x86-64, it isn't for AMD's original (and I'd tend to say that the
> latter is more correct, since afaik there's nowhere that exceptions
> are being made for the meaning of the operand size prefix).
It is also correct for AMD. Otherwise, Linux won't run on AMD
machines since x86-64 TLS uses 0x66 as NOP prefix before