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    SubjectRe: [PATCH 1/2] fs/efivarfs: restrict inode permissions
    On Tue, Feb 20, 2018 at 02:01:51PM -0800, Linus Torvalds wrote:
    > And just on general principlies, I don't want to see weasel-wordy
    > commit messages like
    >
    > "Reading certain EFI variables trigger SMIs"
    >
    > I understand *writing* them causing SMI's due to some flash protection
    > scheme. What's the reading thing? And why aren't we calling that
    > garbage out?

    Too much weasel there. Should say:

    EFI[1] stinks. Reading any file in /sys/firmware/efi/efivars/ generates
    4 (yes FOUR!) SMIs.

    # rdmsr 0x34
    14e2
    # cat /sys/firmware/efi/efivars/ConIn-8be4df61-93ca-11d2-aa0d-00e098032b8c > /dev/null
    # rdmsr 0x34
    14e6

    -Tony

    [1] I didn't dig through the Linux code to check whether we manage to
    get those four SMIs from a single EFI call, or whether we make multiple
    EFI calls to open/read/close one file. It is possible that we stink a
    bit too if we are doing more EFI calls than required.

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