Hi, > From: Hanjun Guo [mailto:hanjun.guo@xxxxxxxxxx] > Sent: Friday, May 09, 2014 4:45 PM > > Hi Lv, > > On 2014-5-9 9:45, Zheng, Lv wrote: > > Hi, > > > > Using size instead of version field to determine FADT version has been talked for many times. > > I didn't see a real case that was persuasive enough to introduce this change. > > Do you have real platforms for us to examine? > > There are some changes for the FADT in the new coming ACPI spec > which changed the field of "reserved4" into other useful information, > and the name of that field was changed also. So if we want to accommodate > that change, we should modify the "reserved4" in the macro of > ACPI_FADT_V2_SIZE too. Is it possible you just write a patch to change the reserved4 and the macro using the new field name after the release of the spec? If not, you can write a patch to change the macros, but don't forget to update the comments for the macros. You could use the field names to replace the constant values in the comments. > If any change to the FADT in the future, we may > modify it again, so I think constant value for the macros would > be better. There might not be such change after the release of the spec. Thanks -Lv > > Thanks > Hanjun > > > > > Thanks and best regards > > -Lv > > > >> From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi-owner@xxxxxxxxxxxxxxx] On Behalf Of Hanjun Guo > >> Sent: Wednesday, May 07, 2014 4:14 PM > >> > >> Hi, > >> > >> I ran into some compile errors when I was prototyping the code > >> for the proposals in ASWG, it turns out that some field in FADT is > >> changed and "reserved4[0]" used in ACPI_FADT_V2_SIZE will > >> cause the error. > >> > >> So my question is that the length of very version of FADT is > >> fixed, why not use a constant value for this puspose? > >> > >> Here is the code: > >> > >> /* > >> * Sizes of the various flavors of FADT. We need to look closely > >> * at the FADT length because the version number essentially tells > >> * us nothing because of many BIOS bugs where the version does not > >> * match the expected length. In other words, the length of the > >> * FADT is the bottom line as to what the version really is. > >> * > >> * For reference, the values below are as follows: > >> * FADT V1 size: 0x074 > >> * FADT V2 size: 0x084 > >> * FADT V3 size: 0x0F4 > >> * FADT V4 size: 0x0F4 > >> * FADT V5 size: 0x10C > >> */ > >> #define ACPI_FADT_V1_SIZE (u32) (ACPI_FADT_OFFSET (flags) + 4) > >> #define ACPI_FADT_V2_SIZE (u32) (ACPI_FADT_OFFSET (reserved4[0]) + 3) > >> #define ACPI_FADT_V3_SIZE (u32) (ACPI_FADT_OFFSET (sleep_control)) > >> #define ACPI_FADT_V5_SIZE (u32) (sizeof (struct acpi_table_fadt)) > >> > >> Why not #define ACPI_FADT_V1_SIZE 0x074 ? > >> Did I miss something? any clarify will be appreciated :) > >> > >> Thanks > >> Hanjun > >> -- > >> 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
