On Tue, 2016-03-01 at 16:03 +0000, Moore, Robert wrote: > We have a bunch of macros in include/acmacros.h -- like this: > > ACPI_MOVE_16_TO_16(d, s) There is a problem in using the ACPICA byte-swap macros. ACPI is little- endian arch, so the macros are set to perform byte-swappings when the CPU arch is big-endian. This case, however, is the other way around. The fields in question are defined & stored as arrays of bytes. If you treat them as multi-bytes numeric values, then you need to byte-swap them when the CPU arch is little-endian because arrays of bytes have the same addressing as big-endian. Another issue is that it is not clear who needs to perform the byte- swapping among ACPICA and drivers. If ACPICA, drivers must agree that these fields are always treated as multi-bytes numeric values despite of the spec. If drivers, we need to make sure that only a single driver performs this byte-swapping one time as ACPI tables are global structures. I think it is much clearer to define the structure according to the ACPI spec. Thanks, -Toshi > > -----Original Message----- > > From: Toshi Kani [mailto:toshi.kani@xxxxxxx] > > Sent: Tuesday, March 01, 2016 8:38 AM > > To: Moore, Robert; rjw@xxxxxxxxxxxxx; Williams, Dan J > > Cc: Zheng, Lv; elliott@xxxxxxx; linux-nvdimm@xxxxxxxxxxxx; linux- > > acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx > > Subject: Re: [PATCH v2 1/3] ACPI/NFIT: Update Control Region Structure > > to > > comply ACPI 6.1 > > > > On Tue, 2016-03-01 at 15:13 +0000, Moore, Robert wrote: > > > > > > > -----Original Message----- > > > > From: Toshi Kani [mailto:toshi.kani@xxxxxxx] > > > > Sent: Monday, February 22, 2016 1:55 PM > > > > To: rjw@xxxxxxxxxxxxx; Williams, Dan J > > > > Cc: Moore, Robert; Zheng, Lv; elliott@xxxxxxx; > > > > linux-nvdimm@xxxxxxxxxxx g; linux-acpi@xxxxxxxxxxxxxxx; > > > > linux-kernel@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; Toshi Kani > > > > Subject: [PATCH v2 1/3] ACPI/NFIT: Update Control Region Structure > > > > to comply ACPI 6.1 > > > > > > > > ACPI 6.1, Table 5-133, updates NVDIMM Control Region Structure as > > > > follows. > > > > - Valid Fields, Manufacturing Location, and Manufacturing Date > > > > are added from reserved range. No change in the structure size. > > > > - IDs defined as SPD values are arrays of bytes. The spec > > > > clarified that they need to be represented as arrays of bytes > > > > as well. > > > > > > > > This patch makes the following changes to support this update. > > > > - Change 'struct acpi_nfit_control_region' to reflect the update. > > > > SPD IDs are defined as arrays of bytes, so that they can be > > > > treated in the same way regardless of CPU endianness and are > > > > not miss-treated as little-endian numeric values. > > > > > > > > > I don't think we are going to start changing the ACPI tables defined > > > in the ACPICA headers because of this. We do in fact have macros for > > > this purpose. > > > > Can you elaborate what macros you suggest to use for this purpose? > > > > Thanks, > > -Toshi > N�����r��y���b�X��ǧv�^�){.n�+����{�i�b�{ay� ʇڙ�,j��f���h���z� �w��� > ���j:+v���w�j�m��������zZ+�����ݢj"��!�i -- 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
