Re: [Qemu-devel] [PATCH v2 1/4] pc: append ssdt-misc.dsl to the DSDT

[Paolo Bonzini <pbonzini@redhat.com>]

On 19/01/2015 16:15, Igor Mammedov wrote:
> On Wed, 24 Dec 2014 17:07:35 +0100
> Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
>> This part of the ACPI tables can vary in size across machine types, but
> s/machine types/QEMU versions/ since it doesn't change its size on machine
> type.

Right.

>> does not depend on the command-line.  It is an SSDT just because it is
> s/does not/its size does not/

Right.

>> the same for i440fx and Q35, and making it an SSDT made the code a bit
> it's in SSDT because we are patching its values and DSDT were supposed
> to stay static (not only size but contents also).
> I'd prefer to keep dynamic part in SSDT to maintain the same separation
> for now.

The DSDT is being patched anyway for the SMC.  So "the DSDT is dynamic,
the SSDT is static" is not something that happens anyway.  The truth is
"the SSDT (apart from ssdt-misc) defines Devices each of which comes
from a template".  This patch removes the "apart from ssdt-misc" part,
and also moves the patching of the SMC out of the per-machine-type AML,
since it is shared anyway.

>> simpler.  However, it also complicates backwards compatibility, so
>> merge it with the DSDT.
> What are these complications?

The complication arises if we want to make the SSDT exactly the same for
all QEMU versions, given a (machine type, command line) pair.  Then you
either cannot do any change to ssdt-misc, or you have to keep different
copies for each machine type.

Paolo