@kas1e
To emulate OS4 under x64 we have two choices: WinUAE for windows users or UAE/QUEMU for linux users.
UAE/WinUAE are based on an old version of QEMU engine, PPC emulation was added as plugin.
You can emulate an Amiga classic with a PPC expansion board and it's fully compatible with OS4.1fe
You can archive a good speed on gfx side setting UAEGFX as board, but it's ok also with Picasso IV board, but in this case you are limited with 4mb ram to 32bit hd resolutions.
Cpu/fpu emulation has some little bugs, all fixed in latest QEMU releases. Sadly both Toni and Frode, as stated on some EAB posts, aren't interested in a new QEMU plugin version and considers OS4 compatibility as a "side effect" adding powerpc board emulation.
So OS4 compatibility is remained without any active support.
On QEMU side we have Sam460ex and Pegasos II boards emulation, but we have more severe limitations because some motherboard features aren't still implemented.
So you have a limited GFX card compatibility and graphics speed is very poor.
Instead CPU/FPU are well emulated and speed is quite good and has no bugs in powerpc instruction emulation.
So to improve/develop further OS4 emulation we need:
for UAE/WinUAE a new plugin version based on latest QEMU sources
for Sam460ex/Pegasos II board a better gfx implementation with also 3d support.
Sadly QEMU project is really hard and complex!
It's not an easy task and to emulate an expansion board like a gfx card or a sound card you should know all it's chipset internals.
There's an active project to emulate a radeon board but it's still incomplete due lack of chip documentation.
https://osdn.net/projects/qmiga/wiki/SubprojectAtihttps://osdn.net/projects/qmiga/wiki/SubprojectPegasos2http://zero.eik.bme.hu/~balaton/qemu/amiga/