DragonFly and 6.x packages

Since DragonFly 6.x is a major number change, there’s no prebuilt packages that match that release number.  As of this writing, the mirror master site shows 5.10 packages, which would work… if that was the next release.  That’s where the number change trips it up.  There should be new 6.x packages in the next few days.  (Thanks to Jan Peter Vogt for the reminder)

Signal safety in DragonFly

Some of the larger application sets on DragonFly have had trouble building, and inconsistent problems with that build.  i.e. rust would fail, but in different parts of the build process, every time.  It looks to be a problem with signal interaction, and there’s now much safer ways to do that on DragonFly.

That is going to require a full buildworld/buildkernel if you are on DragonFly-master, 5.7.  Release/5.6 users are unaffected.

OPIE removal in DragonFly-master

OPIE was disabled recently in DragonFly.  Now that the 5.6 release is out, it has been removed.  This may require manual intervention if you are on DragonFly-master (i.e. 5.5. or 5.7) and update in the next day or two.  This need to fiddle with it will go away soon with changes to ‘make upgrade’; I will mention it when I see it.

This won’t affect anyone running 5.4 or 5.6.  It’s only in development.

HAMMER2 corruption bug and fix

It’s possible to have data corrupted on a HAMMER2 volume during a specific combination of a bulkfree operation and a lot of writing to disk.  Matthew Dillon has a potential fix already.  As he announced, it’s scheduled to go into 5.4 this weekend.  It’s a rare bug, but if you want to check for it, look for CHECK FAIL entries in /var/log/messages.

And because every cloud has a silver lining: some not-yet-quantified performance improvements.

 

More Meltdown fixes

If you’re on the bleeding edge of DragonFly and already updated for Meltdown fixes, there’s a few more commits you’ll want to get.

Matthew Dillon wrote a summary of the current status, noting there’s not much you can do for Spectre beyond new hardware.   There is an update to the “defensive browser setup” plan for DragonFly (using –site-per-process) that can help at least with Javascript versions of Spectre.

Update: step-by-step microcode fixes from Intel if you really want to trash your performance.

Meltdown and Spectre and DragonFly

By now you’ve probably heard of the Meltdown/Spectre attacks.  (background rumors, technical note)  Matthew Dillon’s put together a Meltdown mitigation in DragonFly, done in four commits.

It’s turned off and on by the sysctl machdep.isolated_user_pmap – and defaults to on for Intel CPUs.  Buildworld tests show about a 4-5% performance hit, but that’s only one form of activity, measured, so there will surely be other effects.

Note that Spectre is not mitigated by this commit series, and as I understand it, cannot be realistically fixed in software.

Update: Matthew Dillon posted a summary to users@.

Update 2: He told us so.