Re: [Qemu-devel] [PATCH] target-i386: enable cflushopt/clwb/pcommit instructions

[Xiao Guangrong]

On 08/22/2015 12:05 AM, Eduardo Habkost wrote:
> On Fri, Aug 21, 2015 at 01:05:12PM +0800, Xiao Guangrong wrote:
> > These instructions are used by NVDIMM drivers and the specification
> > locates at:
> > https://software.intel.com/sites/default/files/managed/0d/53/319433-022.pdf
> >
> > Let them be enabled on Broadwell on default
> >
> > Signed-off-by: Xiao Guangrong <address@hidden>
>
> This breaks the ABI. If you change a CPU model you need machine compat
> code (see the TYPE_X86_CPU entries in PC_COMPAT_2_3 for example).
>
> And you can only change the CPU model in a new machine-type if that
> doesn't affect the runnability of a VM. In other words:
>
> If:
>    -machine pc-i440fx-2.4 -cpu <model>,enforcec
> is runnable in a given host, then
>    -machine pc-i440fx-2.5 -cpu <model>,enforce
> should be runnable too.

Eduardo, thanks for your info. I will dig into the code and fix this
issue in the next version.