Hello Bob,

> I think if we can describe the dependency between source files in INF file. For example,
> [Sources.IA32]
>   asl_source.asl
>   c_source.c | asl_source.asl
This looks good to me! Would it be possible to have multiple dependencies on one file (1), or would it be limited to one file only (2)?
Maybe having multiple dependencies like in (1) would make it easier to read:

Example (1):
[Sources.IA32]
asl_source_1.asl
asl_source_2.asl
c_source.c | asl_source_1.asl | asl_source_2.asl

Example (2):
[Sources.IA32]
asl_source_1.asl
asl_source_2.asl | asl_source_1.asl
c_source.c | asl_source_2

> The build tool will generate the dependency that says c_source.c depend on the output of asl_source.asl in Makefile?
> What do you think?
Would there be a rule in the Makefile on c_source.c or on c_source.obj? And how can we describe a dependency on the output of asl_source.asl?

What I thought was that the resulting Makefile dependencies would look like this:
(a) c_source.obj: asl_source.aml

The dependencies between the source files would be converted to Makefile dependencies between their corresponding output format (cf edk2/BaseTools/Conf/build_rule.template).
E.g.: a dependency on a '.dts' file would be converted to a dependency on a '.dtb' file.

Dependencies on file extensions without output format would trigger an error.
E.g.: no dependency on '.h' would be allowed.

The issue with what I am suggesting is that in my case, I am compiling a '.asl' file into a '.hex' file using the iASL compiler with the '-tc' option. This '.hex' file is included in a '.c' file. This means that the dependency is actually between the output of the compiled '.asl' file (so the '.hex' file), and the '.c' file.
I.e.: the 'true' dependency is
(b) c_source.c: asl_source.hex
However, making edk2 know that the asl_source.asl will produce asl_source.hex will lead to modification to the Conf/build_rule.txt, wich is not a good idea neither I believe.

Having (a) instead of (b) should be simpler to obtain, even though less correct.
I don't know what you think about what format should have/
* the target of the Makefile rule (c_source.c or c_source.obj?)
* the prerequisites of the Makefile rule (asl_source.?)

> Would you submit a BZ to track this issue?
Yes, I will do it at the beginning of the week.

Please tell me what do you think,

Regards,
Pierre