kern/57185: Python build fails on 10_BETA due to no entropy on Atom CPU system

[jspath55%gmail.com@localhost]

>Number:         57185
>Category:       kern
>Synopsis:       Python build fails on 10_BETA due to no entropy on Atom CPU system
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          doc-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 16 20:15:00 +0000 2023
>Originator:     Jim Spath
>Release:        10_BETA
>Organization:
>Environment:
NetBSD nnnn 10.0_BETA NetBSD 10.0_BETA (GENERIC) #0: Sat Dec 31 04:55:53 UTC 2022  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC i386 i386 Intel 686-class NetBSD
>Description:
After an upgrade from NetBSD 9 to 10_BETA, a build of python3.10 stalled with no obvious feedback.
On boot, the system showed:

Jan  3 21:07:29 nnnn /netbsd: [   1.0065252] WARNING: system needs entropy for security; see entropy(7)

There were console screen messages about the block which I did not see right away.

One message about the python hang appeared in /var/log/messages during a shutdown:

Jan 11 18:03:44 nnnn /netbsd: [ 176217.1118082] entropy: pid 19289 (python) blocking due to lack of entropy
Jan 11 18:03:44 nnnn /netbsd: [ 339845.8159510] syncing disks... done
Jan 11 18:03:44 nnnn /netbsd: [ 339845.8259565] unmounted procfs on /proc type procfs

After researching, I found suggested workarounds here:

http://mail-index.netbsd.org/current-users/2021/06/14/msg041118.html
http://mail-index.netbsd.org/current-users/2021/06/15/msg041128.html 

After creating a valid seed, the python build completed.
Boot messages show:

Jan 11 18:03:44 nnnn /netbsd: [  15.5957645] entropy: ready

>How-To-Repeat:
Install or upgrade to NetBSD 10 beta with a CPU similar to:

Intel(R) Atom(TM) CPU D425   @ 1.80GHz

Build Python 3.10 from source (i.e. pkgsrc)
>Fix:
Several workarounds exist, such as overriding the system entropy status, or creating a seed file on a compliant system and importing.
I opened this PR as the build stalling reason was unclear at first (no immediate user feedback).