##(see the SpecSpec for an explanation)

 * '''Launchpad Entry''': UbuntuSpec:lpia-versus-i386
 * '''Created''': 20090120
 * '''Contributors''': 
 * '''Packages affected''':

== Summary ==

Is the lpia architecture a necessary pain or is i386 good enough? How many lpia specific changes do we still carry? Can we provide a tool to upgrade existing lpia installs to i386 (or i386 to amd64 or arm to armel...)?  What can we do with the lpia architecture right now?

== Release Note ==

Probably not release notes worthy in the current state.

== Rationale ==

The lpia architecture is a maintenance burden for Ubuntu; we need to make sure it's useful enough or dropped: either by asserting that it is useful enough, or by changing it into something more useful.  The lpia architecture also creates problems of its own (incompatibility with third party .debs).

== Review of the lpia architecture ==

 * Little perceived performance gain
 * Some delta with Debian
 * Incompatibility with third party i386-only .debs
 * Not a clear use case

=== Changes which might warrant keeping lpia ===

 * Additional changes to the toolchain to improve performance for upcoming new
   CPU generation
 * Expected future architecture changes that may benefit from optimisation
 * Incompatible future architectures: actually wont happen anytime soon as
   Moorestown will be binary compatible

=== Compiler flags considerations ===

On some the Moblin list, an Intel person suggested to use:
 * -O3: does not show significant improvement in testing: modprobe is counter-example with -Os
 * SSE: several applications are expected to benefit
 * -static: performance improvements do not justify additional maintenance efforts
 * -march=nocona: implies OOE which Atom is documented not to support - unlikely to be adopted


However the correct flags to use as explained by Rusty Lynch (Moblin) are:
 * -march=core2
 * -mtune=generic
 * -mfpmath=sse
 * -Os
[ citation needed! ]

== Arch conversion tools ==

 Tools would generally need lots of love, and aren't ready yet, but there are some good use cases.

 * archtakeover / debtakeover
  * arm -> armel, but could be repurposed
  * Not complete in Debian, fragile
  * Consider for i386 -> amd64
 * Leverage ubiquity-preserve-home for cross-arch applications

== Follow-up ==

 Keep the lpia architecture in maintenance mode.  Discuss the use of the best compiler flags for lpia with the Ubuntu Foundations Team.

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