On Thu, Jul 31, 2025 at 07:21:37PM +0000, dm...@proton.me wrote: > x86 port of Xen lacks vUART facility similar to Arm's vpl011 to support x86 > guest OS bring up in the embedded setups. > > This patch series introduces initial in-hypervisor emulator for > NS8250/NS16x50-compatible UARTs under CONFIG_VUART_NS16550. > > In parallel domain creation scenario (hyperlaunch), NS16550 emulator helps > early guest firmware and OS bringup debugging, because it eliminates > dependency on the external emulator (qemu) being operational by the time > domains are created. > > The emulator also allows to forward the physical console input to the x86 > domain which is useful when a system has only one physical UART for early > debugging and this UART is owned by Xen. > > By default, CONFIG_VUART_NS16550 enables emulation of NS16550 at I/O port > 0x3f8, IRQ#4 in guest OS (legacy COM1). But all legacy COM resources can be > selected at built-time (no per-domain configuration yet). > > The NS16550 emulator is disabled in default x86 configuration and goes under > CONFIG_EXPERT in menuconfig. > > Limitations > =========== > - Only x86; > - Only HVM domains support (build-time), PVH domains are not supported yet;
I'm confused by the above statement, HVM domains always have an emulated serial provided by QEMU if needed, so I think you got this backwards, and it should instead be: - Only PVH domains supported, PV and HVM domains are not supported yet. ? Thanks, Roger.
