2020-02-17 23:12:00 +07:00
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.. SPDX-License-Identifier: GPL-2.0
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2012-10-04 15:57:31 +07:00
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2020-02-17 23:12:00 +07:00
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=======================================
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2012-10-04 15:57:31 +07:00
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efivarfs - a (U)EFI variable filesystem
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2020-02-17 23:12:00 +07:00
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=======================================
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2012-10-04 15:57:31 +07:00
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The efivarfs filesystem was created to address the shortcomings of
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using entries in sysfs to maintain EFI variables. The old sysfs EFI
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variables code only supported variables of up to 1024 bytes. This
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limitation existed in version 0.99 of the EFI specification, but was
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removed before any full releases. Since variables can now be larger
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than a single page, sysfs isn't the best interface for this.
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Variables can be created, deleted and modified with the efivarfs
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filesystem.
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2020-02-17 23:12:00 +07:00
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efivarfs is typically mounted like this::
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2012-10-04 15:57:31 +07:00
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mount -t efivarfs none /sys/firmware/efi/efivars
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2016-02-09 02:48:15 +07:00
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Due to the presence of numerous firmware bugs where removing non-standard
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UEFI variables causes the system firmware to fail to POST, efivarfs
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files that are not well-known standardized variables are created
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as immutable files. This doesn't prevent removal - "chattr -i" will work -
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but it does prevent this kind of failure from being accomplished
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accidentally.
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