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random: Add comment to random_initialize() 

Many platforms have per-machine instance data (serial numbers,
asset tags, etc.) squirreled away in areas that are accessed
during early system bringup. Mixing this data into the random
pools has a very high value in providing better random data,
so we should allow (and even encourage) architecture code to
call add_device_randomness() from the setup_arch() paths.

However, this limits our options for internal structure of
the random driver since random_initialize() is not called
until long after setup_arch().

Add a big fat comment to rand_initialize() spelling out
this requirement.

Suggested-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
hifive-unleashed-5.1
Tony Luck 2012-07-23 09:47:57 -07:00 committed by Theodore Ts'o
parent b4237003cf
commit cbc96b7594
1 changed files with 10 additions and 0 deletions
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10
drivers/char/random.c
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@ -1087,6 +1087,16 @@ static void init_std_data(struct entropy_store *r)
mix_pool_bytes(r, utsname(), sizeof(*(utsname())), NULL);
}
/*
* Note that setup_arch() may call add_device_randomness()
* long before we get here. This allows seeding of the pools
* with some platform dependent data very early in the boot
* process. But it limits our options here. We must use
* statically allocated structures that already have all
* initializations complete at compile time. We should also
* take care not to overwrite the precious per platform data
* we were given.
*/
static int rand_initialize(void)
{
init_std_data(&input_pool);