linux/Documentation/filesystems/efivarfs.txt
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   2efivarfs - a (U)EFI variable filesystem
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   4The efivarfs filesystem was created to address the shortcomings of
   5using entries in sysfs to maintain EFI variables. The old sysfs EFI
   6variables code only supported variables of up to 1024 bytes. This
   7limitation existed in version 0.99 of the EFI specification, but was
   8removed before any full releases. Since variables can now be larger
   9than a single page, sysfs isn't the best interface for this.
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  11Variables can be created, deleted and modified with the efivarfs
  12filesystem.
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  14efivarfs is typically mounted like this,
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  16        mount -t efivarfs none /sys/firmware/efi/efivars
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  18Due to the presence of numerous firmware bugs where removing non-standard
  19UEFI variables causes the system firmware to fail to POST, efivarfs
  20files that are not well-known standardized variables are created
  21as immutable files.  This doesn't prevent removal - "chattr -i" will work -
  22but it does prevent this kind of failure from being accomplished
  23accidentally.
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