Ryan Houdek
76bd81af15
Currently FEX will always jump out of the JIT any time FCW was getting written to, ensuring that the softfloat state is setup to rounding at the time of FCW getting written. This has the unintended side-effect that even in "x87 reduced precision" mode we were jumping out of the JIT. This hit a real world use case of an installer reloading FCW after every x87 operation and generating a block with 2297 instructions. Instead when jumping out of the JIT for handling x87 operations, load FCW and pass it as the first argument of the handler. Setting the softfloat state at that point. This helps the installer's hottest block by cutting it down to 1477 instructions. 64.3% of the original size. The code block is still burning 90% of the CPU time of the installer but the performance is significantly better while it is doing its decompression. In order to optimize this installer's block of code more then we will likely need to optimize out x87 stack usage.
FEX - Fast x86 emulation frontend
FEX allows you to run x86 and x86-64 binaries on an AArch64 host, similar to qemu-user and box86. It has native support for a rootfs overlay, so you don't need to chroot, as well as some thunklibs so it can forward things like GL to the host. FEX presents a Linux 5.0 interface to the guest, and supports both AArch64 and x86-64 as hosts. FEX is very much work in progress, so expect things to change.
Quick start guide
For Ubuntu 20.04, 21.04, 21.10, 22.04
Execute the following command in the terminal to install FEX through a PPA.
curl --silent https://raw.githubusercontent.com/FEX-Emu/FEX/main/Scripts/InstallFEX.py --output /tmp/InstallFEX.py && python3 /tmp/InstallFEX.py && rm /tmp/InstallFEX.py
This command will walk you through installing FEX through a PPA, and downloading a RootFS for use with FEX.
Ubuntu PPA is updated with our monthly releases.
For everyone else
Please see Building FEX.
Getting Started
FEX has been tested to build and run on ARMv8.0, ARMv8.1+, and x86-64(AVX or newer) hardware. ARMv7 and older x86 hardware will not work. Expected operating system usage is Linux. FEX has been tested with Ubuntu 20.04, 20.10, and 21.04. Also Arch Linux.
On AArch64 hosts the user MUST have an x86-64 RootFS Creating a RootFS.
Navigating the Source
See the Source Outline for more information.
Building FEX
Follow the guide on the official FEX-Emu Wiki here.
RootFS generation
AArch64 hosts require a rootfs for running applications. Follow the guide on the wiki page for seeing how to set up the rootfs from scratch https://wiki.fex-emu.com/index.php/Development:Setting_up_RootFS
