> On 18 Aug 2025, at 18:26, Peter Maydell <peter.mayd...@linaro.org> wrote: > > So, what's the rationale here? QEMU's UART doesn't care about > clocks at all. We provide a clock in the DTB because the kernel > refuses to boot if you don't, but if the ACPI spec didn't even > have a way to pass the clock frequency until rev 4 this obviously > isn't a problem on that side.
The rationale is the same – just as the (Linux?) kernel expects a clock frequency if a UART is present in the DTB, guests using ACPI may expect a valid value for the clock frequency in the SPCR record when one is present. Since we already have to have a notional value in the DTB, it makes sense to expose the same value via ACPI, too, for consistency. The RISC-V virt machine, for example, has it both in its DTB and ACPI DSDT. I’ll fix the other patches per your comments if you think this is worth adding. Thanks, Vadim
