From 0a4cad9c11ad46662ede48d94f08ecb7cd9f6916 Mon Sep 17 00:00:00 2001 From: Enric Balletbo i Serra Date: Fri, 13 May 2022 12:52:09 +0500 Subject: platform/chrome: Add ChromeOS ACPI device driver The x86 Chromebooks have the ChromeOS ACPI device. This driver attaches to the ChromeOS ACPI device and exports the values reported by ACPI in a sysfs directory. This data isn't present in ACPI tables when read through ACPI tools, hence a driver is needed to do it. The driver gets data from firmware using the ACPI component of the kernel. The ACPI values are presented in string form (numbers as decimal values) or binary blobs, and can be accessed as the contents of the appropriate read only files in the standard ACPI device's sysfs directory tree. This data is consumed by the ChromeOS user space. Reviewed-by: Guenter Roeck Reviewed-by: Andy Shevchenko Reviewed-by: Greg Kroah-Hartman Acked-by: Rafael J. Wysocki Signed-off-by: Enric Balletbo i Serra Co-developed-by: Muhammad Usama Anjum Signed-off-by: Muhammad Usama Anjum Signed-off-by: Tzung-Bi Shih Link: https://lore.kernel.org/r/Yn4OKYrtV35Dv+nd@debian-BULLSEYE-live-builder-AMD64 --- .../ABI/testing/sysfs-driver-chromeos-acpi | 126 +++++++ .../firmware-guide/acpi/chromeos-acpi-device.rst | 363 +++++++++++++++++++++ Documentation/firmware-guide/acpi/index.rst | 1 + 3 files changed, 490 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-driver-chromeos-acpi create mode 100644 Documentation/firmware-guide/acpi/chromeos-acpi-device.rst (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi new file mode 100644 index 000000000000..5b59ef9d7b37 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi @@ -0,0 +1,126 @@ +What: /sys/bus/platform/devices/GGL0001:*/BINF.2 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows information about the current boot of + the active EC firmware. + * 0 - Read only (recovery) firmware. + * 1 - Rewritable firmware. + +What: /sys/bus/platform/devices/GGL0001:*/BINF.3 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows information about the current boot of + the active main firmware type. + * 0 - Recovery. + * 1 - Normal. + * 2 - Developer. + * 3 - Netboot (factory installation only). + +What: /sys/bus/platform/devices/GGL0001:*/CHSW +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the switch position for the Chrome OS specific + hardware switches. + * 0 - No changes. + * 2 - Recovery button was pressed when firmware booted. + * 4 - Recovery button was pressed when EC firmware booted. + * 32 - Developer switch was enabled when firmware booted. + * 512 - Firmware write protection was disabled when firmware + booted. + +What: /sys/bus/platform/devices/GGL0001:*/FMAP +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the physical memory address of the start of + the main processor firmware flashmap. + +What: /sys/bus/platform/devices/GGL0001:*/FRID +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the firmware version for the read-only portion + of the main processor firmware. + +What: /sys/bus/platform/devices/GGL0001:*/FWID +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the firmware version for the rewritable portion + of the main processor firmware. + +What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.0 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the type of the GPIO signal for the Chrome OS + specific GPIO assignments. + * 1 - Recovery button. + * 2 - Developer mode switch. + * 3 - Firmware write protection switch. + * 256 to 511 - Debug header GPIO 0 to GPIO 255. + +What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.1 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the signal attributes of the GPIO signal. + * 0 - Signal is active low. + * 1 - Signal is active high. + +What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.2 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the GPIO number on the specified GPIO + controller. + +What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.3 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the name of the GPIO controller. + +What: /sys/bus/platform/devices/GGL0001:*/HWID +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the hardware ID for the Chromebook. + +What: /sys/bus/platform/devices/GGL0001:*/MECK +Date: May 2022 +KernelVersion: 5.19 +Description: + This binary file returns the SHA-1 or SHA-256 hash that is + read out of the Management Engine extended registers during + boot. The hash is exported vi ACPI so the OS can verify that + the Management Engine firmware has not changed. If Management + Engine is not present, or if the firmware was unable to read the + extended registers, this buffer size can be zero. + +What: /sys/bus/platform/devices/GGL0001:*/VBNV.0 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the offset in CMOS bank 0 of the verified boot + non-volatile storage block, counting from the first writable + CMOS byte (that is, 'offset = 0' is the byte following the 14 + bytes of clock data). + +What: /sys/bus/platform/devices/GGL0001:*/VBNV.1 +Date: May 2022 +KernelVersion: 5.19 +Description: + This file shows the size in bytes of the verified boot + non-volatile storage block. + +What: /sys/bus/platform/devices/GGL0001:*/VDAT +Date: May 2022 +KernelVersion: 5.19 +Description: + This binary file returns the verified boot data block shared + between the firmware verification step and the kernel + verification step. diff --git a/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst b/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst new file mode 100644 index 000000000000..f37fc90ce340 --- /dev/null +++ b/Documentation/firmware-guide/acpi/chromeos-acpi-device.rst @@ -0,0 +1,363 @@ +.. SPDX-License-Identifier: GPL-2.0 + +===================== +Chrome OS ACPI Device +===================== + +Hardware functionality specific to Chrome OS is exposed through a Chrome OS ACPI device. +The plug and play ID of a Chrome OS ACPI device is GGL0001. GGL is a valid PNP ID of Google. +PNP ID can be used with the ACPI devices according to the guidelines. The following ACPI +objects are supported: + +.. flat-table:: Supported ACPI Objects + :widths: 1 2 + :header-rows: 1 + + * - Object + - Description + + * - CHSW + - Chrome OS switch positions + + * - HWID + - Chrome OS hardware ID + + * - FWID + - Chrome OS firmware version + + * - FRID + - Chrome OS read-only firmware version + + * - BINF + - Chrome OS boot information + + * - GPIO + - Chrome OS GPIO assignments + + * - VBNV + - Chrome OS NVRAM locations + + * - VDTA + - Chrome OS verified boot data + + * - FMAP + - Chrome OS flashmap base address + + * - MLST + - Chrome OS method list + +CHSW (Chrome OS switch positions) +================================= +This control method returns the switch positions for Chrome OS specific hardware switches. + +Arguments: +---------- +None + +Result code: +------------ +An integer containing the switch positions as bitfields: + +.. flat-table:: + :widths: 1 2 + + * - 0x00000002 + - Recovery button was pressed when x86 firmware booted. + + * - 0x00000004 + - Recovery button was pressed when EC firmware booted. (required if EC EEPROM is + rewritable; otherwise optional) + + * - 0x00000020 + - Developer switch was enabled when x86 firmware booted. + + * - 0x00000200 + - Firmware write protection was disabled when x86 firmware booted. (required if + firmware write protection is controlled through x86 BIOS; otherwise optional) + +All other bits are reserved and should be set to 0. + +HWID (Chrome OS hardware ID) +============================ +This control method returns the hardware ID for the Chromebook. + +Arguments: +---------- +None + +Result code: +------------ +A null-terminated ASCII string containing the hardware ID from the Model-Specific Data area of +EEPROM. + +Note that the hardware ID can be up to 256 characters long, including the terminating null. + +FWID (Chrome OS firmware version) +================================= +This control method returns the firmware version for the rewritable portion of the main +processor firmware. + +Arguments: +---------- +None + +Result code: +------------ +A null-terminated ASCII string containing the complete firmware version for the rewritable +portion of the main processor firmware. + +FRID (Chrome OS read-only firmware version) +=========================================== +This control method returns the firmware version for the read-only portion of the main +processor firmware. + +Arguments: +---------- +None + +Result code: +------------ +A null-terminated ASCII string containing the complete firmware version for the read-only +(bootstrap + recovery ) portion of the main processor firmware. + +BINF (Chrome OS boot information) +================================= +This control method returns information about the current boot. + +Arguments: +---------- +None + +Result code: +------------ + +.. code-block:: + + Package { + Reserved1 + Reserved2 + Active EC Firmware + Active Main Firmware Type + Reserved5 + } + +.. flat-table:: + :widths: 1 1 2 + :header-rows: 1 + + * - Field + - Format + - Description + + * - Reserved1 + - DWORD + - Set to 256 (0x100). This indicates this field is no longer used. + + * - Reserved2 + - DWORD + - Set to 256 (0x100). This indicates this field is no longer used. + + * - Active EC firmware + - DWORD + - The EC firmware which was used during boot. + + - 0 - Read-only (recovery) firmware + - 1 - Rewritable firmware. + + Set to 0 if EC firmware is always read-only. + + * - Active Main Firmware Type + - DWORD + - The main firmware type which was used during boot. + + - 0 - Recovery + - 1 - Normal + - 2 - Developer + - 3 - netboot (factory installation only) + + Other values are reserved. + + * - Reserved5 + - DWORD + - Set to 256 (0x100). This indicates this field is no longer used. + +GPIO (Chrome OS GPIO assignments) +================================= +This control method returns information about Chrome OS specific GPIO assignments for +Chrome OS hardware, so the kernel can directly control that hardware. + +Arguments: +---------- +None + +Result code: +------------ +.. code-block:: + + Package { + Package { + // First GPIO assignment + Signal Type //DWORD + Attributes //DWORD + Controller Offset //DWORD + Controller Name //ASCIIZ + }, + ... + Package { + // Last GPIO assignment + Signal Type //DWORD + Attributes //DWORD + Controller Offset //DWORD + Controller Name //ASCIIZ + } + } + +Where ASCIIZ means a null-terminated ASCII string. + +.. flat-table:: + :widths: 1 1 2 + :header-rows: 1 + + * - Field + - Format + - Description + + * - Signal Type + - DWORD + - Type of GPIO signal + + - 0x00000001 - Recovery button + - 0x00000002 - Developer mode switch + - 0x00000003 - Firmware write protection switch + - 0x00000100 - Debug header GPIO 0 + - ... + - 0x000001FF - Debug header GPIO 255 + + Other values are reserved. + + * - Attributes + - DWORD + - Signal attributes as bitfields: + + - 0x00000001 - Signal is active-high (for button, a GPIO value + of 1 means the button is pressed; for switches, a GPIO value + of 1 means the switch is enabled). If this bit is 0, the signal + is active low. Set to 0 for debug header GPIOs. + + * - Controller Offset + - DWORD + - GPIO number on the specified controller. + + * - Controller Name + - ASCIIZ + - Name of the controller for the GPIO. + Currently supported names: + "NM10" - Intel NM10 chip + +VBNV (Chrome OS NVRAM locations) +================================ +This control method returns information about the NVRAM (CMOS) locations used to +communicate with the BIOS. + +Arguments: +---------- +None + +Result code: +------------ +.. code-block:: + + Package { + NV Storage Block Offset //DWORD + NV Storage Block Size //DWORD + } + +.. flat-table:: + :widths: 1 1 2 + :header-rows: 1 + + * - Field + - Format + - Description + + * - NV Storage Block Offset + - DWORD + - Offset in CMOS bank 0 of the verified boot non-volatile storage block, counting from + the first writable CMOS byte (that is, offset=0 is the byte following the 14 bytes of + clock data). + + * - NV Storage Block Size + - DWORD + - Size in bytes of the verified boot non-volatile storage block. + +FMAP (Chrome OS flashmap address) +================================= +This control method returns the physical memory address of the start of the main processor +firmware flashmap. + +Arguments: +---------- +None + +NoneResult code: +---------------- +A DWORD containing the physical memory address of the start of the main processor firmware +flashmap. + +VDTA (Chrome OS verified boot data) +=================================== +This control method returns the verified boot data block shared between the firmware +verification step and the kernel verification step. + +Arguments: +---------- +None + +Result code: +------------ +A buffer containing the verified boot data block. + +MECK (Management Engine Checksum) +================================= +This control method returns the SHA-1 or SHA-256 hash that is read out of the Management +Engine extended registers during boot. The hash is exported via ACPI so the OS can verify that +the ME firmware has not changed. If Management Engine is not present, or if the firmware was +unable to read the extended registers, this buffer can be zero. + +Arguments: +---------- +None + +Result code: +------------ +A buffer containing the ME hash. + +MLST (Chrome OS method list) +============================ +This control method returns a list of the other control methods supported by the Chrome OS +hardware device. + +Arguments: +---------- +None + +Result code: +------------ +A package containing a list of null-terminated ASCII strings, one for each control method +supported by the Chrome OS hardware device, not including the MLST method itself. +For this version of the specification, the result is: + +.. code-block:: + + Package { + "CHSW", + "FWID", + "HWID", + "FRID", + "BINF", + "GPIO", + "VBNV", + "FMAP", + "VDTA", + "MECK" + } diff --git a/Documentation/firmware-guide/acpi/index.rst b/Documentation/firmware-guide/acpi/index.rst index b053b0c3d696..b6a42f4ffe03 100644 --- a/Documentation/firmware-guide/acpi/index.rst +++ b/Documentation/firmware-guide/acpi/index.rst @@ -29,3 +29,4 @@ ACPI Support non-d0-probe extcon-intel-int3496 intel-pmc-mux + chromeos-acpi-device -- cgit v1.2.3 From a6c13d87b4b7ae7f7f4574014f5478f7fe92540c Mon Sep 17 00:00:00 2001 From: Bagas Sanjaya Date: Wed, 18 May 2022 15:35:23 +0700 Subject: platform/chrome: Use tables for values lists of ChromeOS ACPI sysfs ABI Stephen Rothwell reported htmldocs warning when merging chrome-platform tree: Documentation/ABI/testing/sysfs-driver-chromeos-acpi:2: WARNING: Unexpected indentation. Documentation/ABI/testing/sysfs-driver-chromeos-acpi:11: WARNING: Unexpected indentation. Documentation/ABI/testing/sysfs-driver-chromeos-acpi:22: WARNING: Unexpected indentation. Documentation/ABI/testing/sysfs-driver-chromeos-acpi:56: WARNING: Unexpected indentation. The warning is due to missing blank line separator surrounding values lists. Instead of using lists, use tables to be consistent with rest of sysfs ABI documentation. Link: https://lore.kernel.org/linux-next/20220516213832.19127535@canb.auug.org.au/ Fixes: 0a4cad9c11ad ("platform/chrome: Add ChromeOS ACPI device driver") Reported-by: Stephen Rothwell Cc: Benson Leung Cc: Guenter Roeck Cc: Andy Shevchenko Cc: Greg Kroah-Hartman Cc: Rafael J. Wysocki Cc: Dmitry Torokhov Cc: Enric Balletbo i Serra Cc: Muhammad Usama Anjum Cc: Tzung-Bi Shih Cc: Linux Kernel Mailing List Cc: Linux Next Mailing List Signed-off-by: Bagas Sanjaya Reviewed-by: Muhammad Usama Anjum Signed-off-by: Tzung-Bi Shih Link: https://lore.kernel.org/r/20220518083524.37380-2-bagasdotme@gmail.com [tzungbi: fix the Fixes tag to 12-chars hash.] Signed-off-by: Tzung-Bi Shih --- .../ABI/testing/sysfs-driver-chromeos-acpi | 52 ++++++++++++++-------- 1 file changed, 33 insertions(+), 19 deletions(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi index 5b59ef9d7b37..cce453951700 100644 --- a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi +++ b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi @@ -4,8 +4,11 @@ KernelVersion: 5.19 Description: This file shows information about the current boot of the active EC firmware. - * 0 - Read only (recovery) firmware. - * 1 - Rewritable firmware. + + == =============================== + 0 Read only (recovery) firmware. + 1 Rewritable firmware. + == =============================== What: /sys/bus/platform/devices/GGL0001:*/BINF.3 Date: May 2022 @@ -13,23 +16,28 @@ KernelVersion: 5.19 Description: This file shows information about the current boot of the active main firmware type. - * 0 - Recovery. - * 1 - Normal. - * 2 - Developer. - * 3 - Netboot (factory installation only). + + == ===================================== + 0 Recovery. + 1 Normal. + 2 Developer. + 3 Netboot (factory installation only). + == ===================================== What: /sys/bus/platform/devices/GGL0001:*/CHSW Date: May 2022 KernelVersion: 5.19 Description: This file shows the switch position for the Chrome OS specific - hardware switches. - * 0 - No changes. - * 2 - Recovery button was pressed when firmware booted. - * 4 - Recovery button was pressed when EC firmware booted. - * 32 - Developer switch was enabled when firmware booted. - * 512 - Firmware write protection was disabled when firmware - booted. + hardware switches when the firmware is booted. + + ==== =========================================== + 0 No changes. + 2 Recovery button was pressed. + 4 Recovery button was pressed (EC firmware). + 32 Developer switch was enabled. + 512 Firmware write protection was disabled. + ==== =========================================== What: /sys/bus/platform/devices/GGL0001:*/FMAP Date: May 2022 @@ -58,18 +66,24 @@ KernelVersion: 5.19 Description: This file shows the type of the GPIO signal for the Chrome OS specific GPIO assignments. - * 1 - Recovery button. - * 2 - Developer mode switch. - * 3 - Firmware write protection switch. - * 256 to 511 - Debug header GPIO 0 to GPIO 255. + + =========== ================================== + 1 Recovery button. + 2 Developer mode switch. + 3 Firmware write protection switch. + 256 to 511 Debug header GPIO 0 to GPIO 255. + =========== ================================== What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.1 Date: May 2022 KernelVersion: 5.19 Description: This file shows the signal attributes of the GPIO signal. - * 0 - Signal is active low. - * 1 - Signal is active high. + + == ======================= + 0 Signal is active low. + 1 Signal is active high. + == ======================= What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.2 Date: May 2022 -- cgit v1.2.3 From abd4fd43f2af03e2e852e6b1b98faeee9e3eae55 Mon Sep 17 00:00:00 2001 From: Bagas Sanjaya Date: Wed, 18 May 2022 15:35:24 +0700 Subject: platform/chrome: Use imperative mood for ChromeOS ACPI sysfs ABI descriptions The current descriptions all begin with ("This file shows something") clause, which is incorrect wording since these mean return value from sysfs. Use imperative mood ("Returns something") instead, in line with corresponding ACPI documentation at firmware-guide/. Cc: Benson Leung Cc: Guenter Roeck Cc: Andy Shevchenko Cc: Greg Kroah-Hartman Cc: Rafael J. Wysocki Cc: Dmitry Torokhov Cc: Enric Balletbo i Serra Cc: Muhammad Usama Anjum Cc: Tzung-Bi Shih Cc: Linux Kernel Mailing List Cc: Linux Next Mailing List Signed-off-by: Bagas Sanjaya Reviewed-by: Muhammad Usama Anjum Signed-off-by: Tzung-Bi Shih Link: https://lore.kernel.org/r/20220518083524.37380-3-bagasdotme@gmail.com --- .../ABI/testing/sysfs-driver-chromeos-acpi | 63 +++++++++++----------- 1 file changed, 30 insertions(+), 33 deletions(-) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi index cce453951700..c308926e1568 100644 --- a/Documentation/ABI/testing/sysfs-driver-chromeos-acpi +++ b/Documentation/ABI/testing/sysfs-driver-chromeos-acpi @@ -2,8 +2,7 @@ What: /sys/bus/platform/devices/GGL0001:*/BINF.2 Date: May 2022 KernelVersion: 5.19 Description: - This file shows information about the current boot of - the active EC firmware. + Returns active EC firmware of current boot (boolean). == =============================== 0 Read only (recovery) firmware. @@ -14,8 +13,7 @@ What: /sys/bus/platform/devices/GGL0001:*/BINF.3 Date: May 2022 KernelVersion: 5.19 Description: - This file shows information about the current boot of - the active main firmware type. + Returns main firmware type for current boot (integer). == ===================================== 0 Recovery. @@ -28,8 +26,8 @@ What: /sys/bus/platform/devices/GGL0001:*/CHSW Date: May 2022 KernelVersion: 5.19 Description: - This file shows the switch position for the Chrome OS specific - hardware switches when the firmware is booted. + Returns switch position for Chrome OS specific hardware + switches when the firmware is booted (integer). ==== =========================================== 0 No changes. @@ -43,29 +41,29 @@ What: /sys/bus/platform/devices/GGL0001:*/FMAP Date: May 2022 KernelVersion: 5.19 Description: - This file shows the physical memory address of the start of - the main processor firmware flashmap. + Returns physical memory address of the start of the main + processor firmware flashmap. What: /sys/bus/platform/devices/GGL0001:*/FRID Date: May 2022 KernelVersion: 5.19 Description: - This file shows the firmware version for the read-only portion - of the main processor firmware. + Returns firmware version for the read-only portion of the + main processor firmware. What: /sys/bus/platform/devices/GGL0001:*/FWID Date: May 2022 KernelVersion: 5.19 Description: - This file shows the firmware version for the rewritable portion - of the main processor firmware. + Returns firmware version for the rewritable portion of the + main processor firmware. What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.0 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the type of the GPIO signal for the Chrome OS - specific GPIO assignments. + Returns type of the GPIO signal for the Chrome OS specific + GPIO assignments (integer). =========== ================================== 1 Recovery button. @@ -78,7 +76,7 @@ What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.1 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the signal attributes of the GPIO signal. + Returns signal attributes of the GPIO signal (integer bitfield). == ======================= 0 Signal is active low. @@ -89,52 +87,51 @@ What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.2 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the GPIO number on the specified GPIO + Returns the GPIO number on the specified GPIO controller. What: /sys/bus/platform/devices/GGL0001:*/GPIO.X/GPIO.3 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the name of the GPIO controller. + Returns name of the GPIO controller. What: /sys/bus/platform/devices/GGL0001:*/HWID Date: May 2022 KernelVersion: 5.19 Description: - This file shows the hardware ID for the Chromebook. + Returns hardware ID for the Chromebook. What: /sys/bus/platform/devices/GGL0001:*/MECK Date: May 2022 KernelVersion: 5.19 Description: - This binary file returns the SHA-1 or SHA-256 hash that is - read out of the Management Engine extended registers during - boot. The hash is exported vi ACPI so the OS can verify that - the Management Engine firmware has not changed. If Management - Engine is not present, or if the firmware was unable to read the - extended registers, this buffer size can be zero. + Returns the SHA-1 or SHA-256 hash that is read out of the + Management Engine extended registers during boot. The hash + is exported via ACPI so the OS can verify that the Management + Engine firmware has not changed. If Management Engine is not + present, or if the firmware was unable to read the extended registers, this buffer size can be zero. What: /sys/bus/platform/devices/GGL0001:*/VBNV.0 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the offset in CMOS bank 0 of the verified boot - non-volatile storage block, counting from the first writable - CMOS byte (that is, 'offset = 0' is the byte following the 14 - bytes of clock data). + Returns offset in CMOS bank 0 of the verified boot non-volatile + storage block, counting from the first writable CMOS byte + (that is, 'offset = 0' is the byte following the 14 bytes of + clock data). What: /sys/bus/platform/devices/GGL0001:*/VBNV.1 Date: May 2022 KernelVersion: 5.19 Description: - This file shows the size in bytes of the verified boot - non-volatile storage block. + Return the size in bytes of the verified boot non-volatile + storage block. What: /sys/bus/platform/devices/GGL0001:*/VDAT Date: May 2022 KernelVersion: 5.19 Description: - This binary file returns the verified boot data block shared - between the firmware verification step and the kernel - verification step. + Returns the verified boot data block shared between the + firmware verification step and the kernel verification step + (binary). -- cgit v1.2.3