+ #define ACPI_REDUCED_HARDWARE TRUE The intent of this feature is of course, to remove all code that is not needed -- specifically for hardware-reduced machines where the size of the kernel is important. On a larger machine, the hardware-reduced flag should be sufficient. However, I would think that the host OS would look at this flag and realize that it should not be doing certain ACPI hardware-related things up front, rather than later when it finds out that a write to some ACPI hardware fails because the hardware isn't there. This is not to say that it is probably a good thing to return an error from the ACPI hardware code in the hardware-reduced case. Bob > -----Original Message----- > From: Hanjun Guo [mailto:hanjun.guo@xxxxxxxxxx] > Sent: Sunday, September 15, 2013 7:40 PM > To: Moore, Robert > Cc: 'Rafael J. Wysocki'; 'Len Brown'; Box, David E; Zheng, Lv; 'linux- > acpi@xxxxxxxxxxxxxxx'; 'patches@xxxxxxxxxx'; 'linaro- > kernel@xxxxxxxxxxxxxxxx'; 'linaro-acpi@xxxxxxxxxxxxxxxx' > Subject: Re: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware to > prevent accessing PM registers > > On 2013-9-14 4:16, Moore, Robert wrote: > > > > > >> -----Original Message----- > >> From: Moore, Robert > >> Sent: Friday, September 13, 2013 6:08 AM > >> To: Hanjun Guo; Rafael J. Wysocki; Len Brown > >> Cc: Zheng, Lv; linux-acpi@xxxxxxxxxxxxxxx; patches@xxxxxxxxxx; > >> linaro- kernel@xxxxxxxxxxxxxxxx; linaro-acpi@xxxxxxxxxxxxxxxx > >> Subject: RE: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware to > >> prevent accessing PM registers > >> > >> NOT_IMPLEMENTED refers to the software only; therefore AE_SUPPORT > >> should be returned. > >> > >> Otherwise, seems like this may be a good idea. > > > > > > On the other hand, could one not argue that the host OS should darn > > well know that it is executing on a hardware-reduced platform and not > > call these functions in the first place? > > Well, there is a macro ACPI_REDUCED_HARDWARE and used to switch off the > compiling of these functions on hardware-reduced platform, if > ACPI_REDUCED_HARDWARE is TRUE, those functions will never be called. > > But is that reasonable? When somebody want to use the ACPI code on > hardware-reduced platform, they should introduce a patch just like: > > - #define ACPI_REDUCED_HARDWARE FALSE > + #define ACPI_REDUCED_HARDWARE TRUE > in include/acpi/acconfig.h > > and this patch does not exist in upstream, and it will never be accepted > by upstream too, it is weird. so we should proposal another way. > > I thought about introducing a kernel config such as > CONFIG_ACPI_REDUCED_HARDWARE to enable ACPI_REDUCED_HARDWARE, but it is > just the same as a macro, and I drop it. > > So, this is a problem should be solved for hardware-reduced platform, use > falg acpi_gbl_reduced_hardware seems a good solution. > > Thanks > Hanjun > > > > > Bob -- 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
