Re: fix for no ssh
Hi.
On Thu, Jul 11, 2019 at 03:00:57PM +0000, Andy Smith wrote:
> On Thu, Jul 11, 2019 at 05:12:03PM +0300, Reco wrote:
> > On Thu, Jul 11, 2019 at 12:03:53PM +0000, Andy Smith wrote:
> > > I think the wiki article at
> > > https://wiki.debian.org/BoottimeEntropyStarvation really shows that
> > > currently there is no such consensus available, as every solution
> > > listed (except buying extra entropy hardware)
> >
> > That one is bad too.
> > Hardware random generator is not used by kernel directly, it requires
> > userspace program (such as hwrngd).
> > So, even if you put it into initrd alongside with the needed kernel
> > modules, there's still a noticeable delay between 'kernel rng is needed'
> > and 'sufficient entropy is available'.
>
> With no modifications and RDRAND instruction disabled,
RDRAND is an exception to this as kernel does use it directly if
allowed. Devices that I wrote about are exposed to userspace via
/dev/hwrng character device.
For instance, this Exynos ARM SOC comes with HWRNG, but:
[ 0.000000] random: get_random_bytes called from start_kernel+0x9c/0x528 with crng_init=0
[ 0.772543] random: fast init done
[ 9.006398] random: lvm: uninitialized urandom read (4 bytes read)
[ 10.206032] random: lvm: uninitialized urandom read (4 bytes read)
[ 10.363308] random: lvm: uninitialized urandom read (4 bytes read)
[ 10.439771] random: lvm: uninitialized urandom read (2 bytes read)
[ 12.322888] random: lvmconfig: uninitialized urandom read (4 bytes read)
[ 12.861180] random: systemd: uninitialized urandom read (16 bytes read)
[ 12.878890] random: systemd: uninitialized urandom read (16 bytes read)
[ 14.126267] random: crng init done
[ 14.714783] exynos-trng 10830600.rng: Exynos True Random Number Generator.
Note that the kernel needs entropy from the beginning, but gets the
possibility to use HWRNG on 14th second of uptime.
Reco
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