ChibiOS Free Embedded RTOS

Well, as you pointed out, ChibiOS it's actually a deterministic real-time OS, but it's not a soft or hard real-time os, and that is what I mean.
The definition of Real-Time OS it's a bit tricky..
An RTOS that can usually or generally meet a deadline is a soft real-time OS, but if it can meet a ...

I'm talking about hard real-time with a fixed priority scheduler like Rate Monotonic (because its easier to implement on a non real-time fixed priority kernel like ChibiOS than a dynamic priority scheduler like EDF), and soft real-time support through a cpu reservation server like Sporadic server.

I don't think so, just take a look at projects like Nano-RK or Erika (there is also Hartik).
In the past I have extended Keil RTX with an EDF scheduler, a Constant Bandwidth Server and SRP protocol, and it works pretty well on a cortex-m.
A fixed priority scheduler is easier to implement, and should ...

What about fixed priority real-time support (rate monotonic) with a cpu reservation server like Sporadic server?