I think I understand what you're trying to achieve and I don't have objections
agaist the goal, but the matter is *how* to do that.
Why don't you do something like this:
(1) Introduce two new functions that will each do part of
acpi_tb_parse_root_table() such that calling them in sequence, one right
after the other, will be exactly equivalent to the current
acpi_tb_parse_root_table().
(2) Redefine acpi_tb_parse_root_table() as a wrapper calling those two new
function one right after the other.
(3) Make Linux use the two new functions directly instead of calling
acpi_tb_parse_root_table()?
Then, Linux will use your new functions and won't call acpi_tb_parse_root_table()
at all, but the other existing users of ACPICA may still call it without any
modifications.
Does this make sense to you?