Jared> [P]erhaps [...] a dom0_mem of 16Mb [is] not a good default Jared> value?

Keir> Sensible defaults are probably either a fixed proportion of Keir> total system RAM, or just to print an error and hang. Either Keir> of these is easy to implement.

Given only those two choices, I definitely think that "require dom0_mem to be set otherwise error out" is the preferred choice.

Using a percentage of total RAM seems error-prone and will cause even more community problems because of different behaviors on different machines. (In other words, you'll now need to ask not only "what did you set dom0_mem to?", but also "how much total is available?"). If the default is say 25%, then a 64Mb machine is right back to the problematic 16Mb, while a 2Gb machine would reserve an unneeded half-a-gig. Correctness and consistency should come first, so I think the "percentage of available" approach should be rejected (though supporting a "dom0_mem=25%" would be a reasonable enhancement).

I personally still think that having an actual value for a default would be somewhat preferred over "dom0_mem is now a required parameter", as that's a behavior change instead of a simple tuning. Since all the documentation already says "dom0_mem=131072", simply setting that to be the default would likely generate the "least suprise" for users and work in almost all cases.

Ultimately, it's strictly a matter of opinion, and the community is unlikely to provide a clear consensus as to the "best" approach. If a change seems warranted based on the recurring FAQs, I'm sure the development team will make an appropriate choice.

"Truth is a great flirt." -- Franz Liszt