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    SubjectRe: [PATCH] Allow hwrng to initialize crng.
    On Wed, Sep 26, 2018 at 11:24:55AM +0800, Louis Collard wrote:
    > Some systems, for example embedded systems, do not generate
    > enough entropy on boot through interrupts, and boot may be blocked for
    > several minutes waiting for a call to getrandom to complete.
    >
    > Currently, random data is read from a hwrng when it is registered,
    > and is loaded into primary_crng. This data is treated in the same
    > way as data that is device-specific but otherwise unchanging, and
    > so primary_crng cannot become initialized with the data from the
    > hwrng.
    >
    > This change causes the data initially read from the hwrng to be
    > treated the same as subsequent data that is read from the hwrng if
    > it's quality score is non-zero.
    >
    > The implications of this are:
    >
    > The data read from hwrng can cause primary_crng to become
    > initialized, therefore avoiding problems of getrandom blocking
    > on boot.
    >
    > Calls to getrandom (with GRND_RANDOM) may be using entropy
    > exclusively (or in practise, almost exclusively) from the hwrng.
    >
    > Regarding the latter point; this behavior is the same as if a
    > user specified a quality score of 1 (bit of entropy per 1024 bits)
    > so hopefully this is not too scary a change to make.
    >
    > This change is the result of the discussion here:
    > https://patchwork.kernel.org/patch/10453893/
    >
    > Signed-off-by: Louis Collard <louiscollard@chromium.org>

    Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

    /Jarkko

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