On Tuesday, February 18, 2014 12:51:07 PM H. Peter Anvin wrote: > On 02/18/2014 10:44 AM, Thomas Renninger wrote: > > On Tuesday, February 18, 2014 10:27:23 AM H. Peter Anvin wrote: > >> Why can't you add SSDTs? It would be particularly useful. > > > > There are 2 ways how ACPI tables get added: > > - Via pointer from a root table (XSDT or RSDT iirc) > > - Via load statement inside of ACPI context when ACPI BIOS > > > > code gets executed (iirc the physical address is passed). > > > > The latter is only for SSDTs. > > The problem is that you if you add an SSDT early, it might > > have been intended for overriding when an SSDT gets dynamically > > loaded later when the system is up which is particular useful as > > well if you want to debug this specific BIOS table. > > > > This could be workarounded via a boot param: > > acpi=allow_ssdt_adding > > But this is not nice. Maybe someone has a more elegant idea. > > Something could still be added if someone is really needing this. > > Since adding SSDTs is one of the things I really can imagine one would > do, I think we need to figure out how to do that. I would think that > overriding would be the exception case.
You can always paste new code into the DSDT. It is effectively the same than adding a new SSDT table. The other way around, modifying or deleting broken code in a BIOS provided SSDT needs overriding. So in fact adding SSDTs is not necessary at all. It would be a nice add-on, but it's not even worth introducing an extra boot param or whatever confusion. A hint in Documentation that adding additional ASL (ACPI Source Language) code to the DSDT would be the same than creating and adding a new SSDT table which is not possible should be enough. The whole thing will always taint the kernel and is meant for debugging only anyway. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
