Alyssa Rosenzweig
2dcae23776
Many flag-generating instructions like cmp need to save calculations for deferred PF and AF flag calculation. Currently, they require a store per flag, which is prohibitively expensive for hot instructions like cmp. By instead pinning PF/AF temporary results to registers (x26/x27 by convention here), we eliminate many stores altogether and turn the rest into zero-cycle moves (on 64-bit at least, this isn't optimal for 32-bit emulation due to CTX->GetGPRSize shenanigans, need to check if this requirement can be lifted..). To implement, we model as SRA and then the existing SRA code is able to generate good code with little manual tuning. (Future work will get us to excellent code with more tuning ;) ). The tradeoff is reducing the working dynamic GPR set by 2 registers, which might increase spilling in some cases. I think it's worth it in practice, though. Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
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
