[ros-dev] Merging our x86 HALs

[Colin Finck]

Hi all,

I have been looking into our HALs recently on the promise that it is a
huge mess that needs fixing. Well, as a start I could imagine merging
our 6 possible x86 HALs (Legacy, ACPI, APIC, ACPI+APIC, SMP, SMP+ACPI)
into a single one, even if Windows ships individual ones. I see many
advantages of that:

* Less duplications and reduced mess: Right now, the APIC HAL hangs at
HalpCalibrateStallExecution during boot, a function that has been fixed
and universally implemented in all non-APIC HALs. The APIC HAL also
duplicates HalpInitializePICs as HalpInitializeLegacyPIC.
If you look at the SMP code, it didn't even receive the last build
system changes and has conflicting implementations for APIC functions.
A single x86 HAL would ensure that all possible configurations are
maintained.

* Future-proof: How is one going to implement newer features like x2APIC
with a structure like that? Would it get another HAL, be integrated into
the APIC HAL, or what?
We wouldn't have such problems with a single x86 HAL.

* Less setup work and testing: Currently, 1st stage setup detects the
computer type and installs the appropriate HAL. As such, every
additional HAL needs to be added to 1st stage setup code.
The user is also able to select a custom HAL during setup, even if it
wouldn't work on the machine. We should give neither the user nor the
setup the ability to decide. The HAL itself knows best at boot-up what
features to enable and what not.

* Convenience: The same ReactOS installation could be used on several
different x86 computers.


So is this the way to go or do I miss something important?


Best regards,

Colin