Architecturally, this was the design of ACPICA -- that anything OS-dependent would be written in whatever format/style/exception model/threading model/blah as the host OS. We even discussed having an interface layer in order to translate incoming requests (to ACPICA) from the host drivers to ACPICA requests, and then translate the output (such as exception codes) back to the host format, but we ended up deciding that this was overkill. I certainly agree that it is not a good idea to mix exception code spaces. Bob > -----Original Message----- > From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- > owner@xxxxxxxxxxxxxxx] On Behalf Of Patrick Mochel > Sent: Wednesday, April 19, 2006 10:28 AM > To: Accardi, Kristen C > Cc: Prarit Bhargava; Andrew Morton; Brown, Len; greg@xxxxxxxxx; linux- > acpi@xxxxxxxxxxxxxxx; pcihpd-discuss@xxxxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; arjan@xxxxxxxxxxxxxxx; > muneda.takahiro@xxxxxxxxxxxxxx; pavel@xxxxxx; temnota@xxxxxx > Subject: Re: [patch 1/3] acpi: dock driver > > On Wed, Apr 19, 2006 at 10:08:57AM -0700, Kristen Accardi wrote: > > On Tue, 2006-04-18 at 15:54 -0700, Patrick Mochel wrote: > > > > > +acpi_status > > > > +register_hotplug_dock_device(acpi_handle handle, > acpi_notify_handler handler, > > > > + void *context) > > > > > > If this is called from outside drivers/acpi/, you should return an int > with a > > > real errno value. The AE_* values shouldn't be used outside of the > ACPI CA. > > > > > > > Really? We use these all over the place in drivers/pci/hotplug. In > > fact, you kinda have to use them if you are calling certain acpi > > symbols, since they return these types. > > > > For example, here are some functions will return acpi_status that we use > > in hotplug land. > > > > pci_osc_control_set() > > acpi_run_oshp() > > acpi_walk_namespace requires its use. > > Well, it's one thing to use a function that returns a non-standard error- > value, > but it's another to add more functions that do. :-) > > > I felt that by returning acpi_status I was being consistent with how > > other acpi calls acted. Is this another example of the iceberg that Len > > was talking about in a previous email?? (ugh.) > > I believe so. > > We have a standard, well-defined error namespace that lives in > include/*/errno.h. > ACPI defines its own error namespace because it must be portable, and even > though > most OSes will define the standard errno values, some do not, so it cannot > assume that it will be there. I'm not sure why the choice was to redefine > similar > error values instead of reusing the errno values, but that's moot at this > point.. > > The only place where the ACPI error values need to be used is in the ACPI > CA. The > functions exposed to the OS from the CA will return AE_* because the same > source > runs everywhere. However, Linux-specific code doesn't need to do that. It > is free > to use Linux-specific error reporting (except in the OSL layer that the CA > uses, > because it is expecting well-defined return values, as specified in the CA > Programmers Reference). > > My standpoint is that Linux-specific code should not be using any ACPI > CAisms at > all because since the code is Linux-specific, it doesn't need to be > portable in > the same manner that the CA is. This is true for all of drivers/acpi/*.c, > with the > exception of drivers/acpi/osl.c, but even some of that source can be > cleaned up > to be more Linux-friendly. > > Further rationale is that there is no way to enforce the CAisms in Linux- > specific > code. You will frequently find mixed return values. Sometimes a function > is > declared as > > acpi_status acpi_foo() > > and return -1 and 0. Or vice versa. > > The ACPI drivers were initially written in the same style that the CA was > written, > which makes it confusing when you look at them. But, they don't need to be > that > way. They can look like real Linux drivers and become a lot more > palatable. > > Eventually, all of the CAisms should be pushed down to the thin layer that > sits > above the interpreter. All exported functions should return ints, and > those that > deal directly with the CA interface should simply translate the AE_* error > values into an errno return. > > Thanks, > > > Pat > > - > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
