> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel- > owner@xxxxxxxxxxxxxxx] On Behalf Of Dan Williams > Sent: Tuesday, June 19, 2018 10:29 AM > Subject: Re: [PATCH v3 1/2] acpi/nfit: Update nfit driver to comply with > ACPI 6.1 ... > > > > Here are some examples (kernel 4.17): Note that these values were as reported on a little-endian system. > Ok, so the lowest significant byte of the Micron id is supposed to be > 0x2c and this text representation matches that. So the bytes are being > endian swapped when written to the SPD? SPD byte 320 is 0x80. That's the bank number byte (with odd parity). SPD byte 321 is 0x2c. That's the manufacturer code byte (with odd parity). If treated as a single 2-byte value, that is: * 0x802c (32812 in decimal) if interpreted as big-endian * 0x2c80 (11392 in decimal) if interpreted as little-endian Reviewing the _show() functions in drivers/acpi/nfit/core.c: BE device:0x314e NE dsm_mask:0x3c76 NE family:1 N/A flags:smart_notify LE format:0x0101 N/A formats:1 BE handle:0x1 BE id:802c-0f-1612-122f8255 [SPD bytes 320-328] NE phys_id:0x16 BE rev_id:0x3100 BE serial:0x122f8255 BE subsystem_device:0x3141 BE subsystem_rev_id:0x0100 BE subsystem_vendor:0x8034 [Cypress Semiconductor] BE vendor:0x802c [Micron] (BE=fixed big-endian, LE=fixed little-endian, NE=native-endian, N/A=not applicable) BE and LE will print the same regardless of the endianness of the system, while NE will vary. Reviewing the NE sysfs files: phys_id: This NFIT field reports an SMBIOS handle (instance ID), a LE number from 0..n (0x103 on one of my systems). dmidecode shows handles like this: Handle 0x0016, DMI type 17, 40 bytes Memory Device Array Handle: 0x000A On a big-endian system, I think we'll see phys_id:0x1600 which means 5632 decimal, which is misleading. Fixed LE would be better. dsm_mask: The code that parses _DSM function 0 output, acpi_check_dsm(), correctly interprets the bitmask as little-endian for internal calculations. I think a big-endian system will print dsm_mask:0x763c, which is confusing. Fixed LE would be better. The override_dsm_mask module parameter needs to match. family: This is an internal value, so NE is fine. ��.n��������+%������w��{.n�����{�����ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
