Date: Thu, 11 Jan 2001 22:49:02 +0200 From: Sheldon Hearn <sheldonh@uunet.co.za> To: Jordan Hubbard <jkh@winston.osd.bsdi.com> Cc: obrien@freebsd.org, Doug Barton <dougb@freebsd.org>, cvs-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/etc crontab rc src/etc/defaults rc.conf src/etc/mtree BSD.root.dist src/libexec Makefile src/libexec/save-entropy Makefile save-entropy.sh Message-ID: <10300.979246142@axl.fw.uunet.co.za> In-Reply-To: Your message of "Thu, 11 Jan 2001 12:36:23 PST." <19283.979245383@winston.osd.bsdi.com>
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On Thu, 11 Jan 2001 12:36:23 PST, Jordan Hubbard wrote: > I also appreciate the arguments for having /var be "too late" in the > boot process, at least as things currently stand, but simply assuming > that root is writable as your work-around isn't a very safe solution > either. *sigh* I made a mistake in not explaining the situation _fully_ right at the beginning. I assumed that people would actually _look_ at rc as it was before and after this commit before commenting. :-( So... Before Doug's commit: Because of limitations in mount_mfs(8), the entropy seed files could not be stored in /var/db/ without causing a hang on post-crash startup. The hang would persist until a sufficient amount of keyboard activity was registered by the entropy device. Therefore, the entropy seed file was stored in / by rc.shutdown. On startup, rc would try to read this file. On failure, it would fall back to trying /var/db/, but this behaviour would still enjoy the hang. Also, a crash would mean that rc.shutdown would not store the entropy seed file at all! This system did _NOT_ cater completely for read-only root partitions. After Doug's commit: Now, cron(8) stores entropy seed files in /.entropy . We can't use /var/db/ yet because of (at least) the same mount_mfs(8) problems we had before problems. Since multiple files are used, there is no race condition and we can rest assured that, even after a crash, there will always be entropy seed files available on startup. This system still does not cater completely for read-only root partitions. In the future: When those mount_*(8) utilities that require entropy (currently, mount_mfs(8) and mount_nfs(8) are the only suspects) have been modified to avoid using the new entropy device, all we'll need to do is swing the rc.conf variable entropy_dir from /.entropy/ to /var/db/ . This system _WILL_ cater completely for read-only root partitions. I trust that this clears up the hype. :-) Seriously, folks, what Doug has implemented is no worse than what we had before and is a step toward something much better than what we had before. Ciao, Sheldon. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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