[Qemu-discuss] Is x86_64 emulation on ARM much slower than x86 emulation?

[Johannes Riecken]

Hi,

I don't know if this is the appropriate place to ask, but I noticed that
upcoming Windows 10 ARM PCs running on Snapdragon 835 only support 32-bit
emulation for x86. Could that be because the performance of x86_64 machine
code dynamically binary translated to ARMv8 is too poor?

As that chipset also supports 64-bit, I assume the addressable space and
number of registers are similar. Could you give an example of how the
micro-ops and translated host code differ for x86 and x86_64 and how many
cycles these operations need?

With kind regards,

Johannes