/dev/io , /dev/mem : only used by Xorg?

Kris Kennaway kris at obsecurity.org
Mon Feb 28 20:13:11 GMT 2005

On Mon, Feb 28, 2005 at 04:58:02AM -0800, Ted Mittelstaedt wrote:

> Yes - there's some random testing suites on the Internet, find a
> few and compile them. (ENT for example) Run them repeatedly and see what
> happens.
> Part of the problem is that BY DEFAULT the random device DOES NOT
> look at interrupts.  See the man page for rndcontrol.  Presumably
> the system admin of the system knows this and looks at his dmesg
> output to see which irq's are assigned to network cards and hard
> disks (which are fairly good sources of randomness) and sets the
> random device to use these.  In practice this isn't something mentioned
> in the install docs so it is very unlikely many people know.
> Another strange thing is that /dev/random should block when it
> runs out of entropy - it doesen't seem to do so, however.  And the
> device doesen't seem to gain entropy that quickly.

No, it should not block because it's not defined to block and that
would be a bad interface anyway.  It does return as many bytes as it
can, and if the application wants more entropy than given then it can
either poll, or fall back to alternative mechanisms as it sees fit
(blocking would prevent this).

Anyway, all your concerns are moot for 5.x.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-questions/attachments/20050228/62917a4c/attachment-0001.bin

More information about the freebsd-questions mailing list