[Qemu-devel] Kernel requirement for membarriers feature

[Kim Højgaard-Hansen]

Hi,

When the membarriers feature was introduced, the kernel requirement was set
to 4.14, however if my understanding of what is needed is correct that is
rather strict?

http://lists.gnu.org/archive/html/qemu-devel/2018-03/msg02748.html

As far as i can tell the feature was introduced in 4.3 see:
https://elixir.bootlin.com/linux/v4.3.6/ident/MEMBARRIER_CMD_SHARED

If I patch out that requirement Qemu also seems to run just fine, with SMP
enabled (should hit the runtime check?) on a 4.9 LTS kernel.

Can someone provide insights into why the requirement is set to 4.14?

Br,
Kim