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Re: PATCH: PR gas/1874: mwait/monitor don't work in 64bit
On Wed, Nov 16, 2005 at 06:12:30PM +0100, Jan Beulich wrote:
> >Are you saying "monitor %eax,%ecx,%edx" should be allowed in 64bit
> >mode? Why? How will it be used?
>
> Just like any other 32-bit addressing in 64-bit mode: probably rarely,
> but it should be allowed for whoever is able to find meaningful use for
> this. We also don't disallow 16-bit addressing in 32-bit mode, even
> though it's unlikely to ever be used...
I disagree. In 64bit mode, the correct way to use monitor is
load %rax
load %edx
load %ecx
monitor %rax, %edx, %ecx # It is the same as "monitor".
It is misleading and confusing to do
load %eax
load %edx
load %ecx
monitor %eax, %edx, %ecx
Assembler will generate the same opcode for those forms anyway. I don't
see why "monitor %eax, %edx, %ecx" has to be allowed in 64bit.
H.J.