Re: Xen Project policy on feature flags

[George Dunlap <george.dunlap@eu.citrix.com>]

On 09/26/2014 03:49 PM, Stefano Stabellini wrote:
>> Let me rephrase - will it boot in the same fashion (And with the same
>> bugs) as it did prior to this functionality being introduced?
> 3.15 -> dom0 on ARM broken (if netback is used)
> 3.17 -> dom0 on ARM is fixed, only if the kernel is compiled with CONFIG_ARM_LPAE
>
> Reverting the XENFEAT_grant_map_identity related changes would give you
> a system broken even with CONFIG_ARM_LPAE.
> Reverting Zoltan's changes to netback would give you a working system.

So the *only* reason to include this flag at this point is to allow 
people to run an unmodified 3.17 kernel with netback, is that right?  It 
seems like a really jerk move to encourage people to put 3.17 on their 
systems, and then deliberately break it on a subsequent release.

Particularly with ARM, where people are used to doing platform-specific 
things, it seems like encouraging people to either use pre-3.15 or to 
revert Zoltan's changes would be a better option.

  -George