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Slim Bootloader(SBL) is a small open-source boot firmware, designed for running on certain Intel platforms. SBL can be thought-of as fulfilling the role of a minimal BIOS implementation, i.e initializing the hardware and booting Operating System. Since SBL is not UEFI compliant, firmware update cannot be triggered using standard UEFI runtime services. Further considering performance impact, SBL doesn't look for a firmware update image on every reset and does so only when firmware update signal is asserted. SBL exposes an ACPI-WMI device which comes up in sysfs as /sys/bus/wmi/44FADEB1xxx and this driver adds a "firmware_update_request" device attribute. This attribute normally has a value of 0 and userspace can signal SBL to update firmware, on next reboot, by writing a value of 1 like: echo 1 > /sys/bus/wmi/devices/44FADEB1xxx/firmware_update_request This driver only implements a signaling mechanism, the actual firmware update process and various details like firmware update image format, firmware image location etc are defined by SBL and are not in the scope of this driver. DocLink: https://slimbootloader.github.io/security/firmware-update.html Signed-off-by: Jithu Joseph <jithu.joseph@intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
12 lines
533 B
Text
12 lines
533 B
Text
What: /sys/bus/wmi/devices/44FADEB1-B204-40F2-8581-394BBDC1B651/firmware_update_request
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Date: April 2020
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KernelVersion: 5.7
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Contact: "Jithu Joseph" <jithu.joseph@intel.com>
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Description:
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Allow user space entities to trigger update of Slim
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Bootloader (SBL). This attribute normally has a value
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of 0 and userspace can signal SBL to update firmware,
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on next reboot, by writing a value of 1.
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There are two available states:
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* 0 -> Skip firmware update while rebooting
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* 1 -> Attempt firmware update on next reboot
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