Messages in this thread | | | Date | Wed, 11 Jul 2012 10:20:18 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 00/36] AArch64 Linux kernel port |
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* Arnd Bergmann <arnd@arndb.de> wrote:
> > Do you really think that all of the 32-bit ARM code should > > essentially be thrown away when going to 64-bit ARM, that > > patches can only touch arch/arm64/ + drivers/ or the > > highway? > > Yes.
Straight answer ;-)
> If you're curious, please have a look at > arch/arm/mach-spear13xx/. this is the latest platform that we > have added. [...]
Very nice.
> [...] It's fully functional (except PCI, which I hope will be > added in drivers/pci/bus, which is another story), A > significant portion of that platform deals with SMP support, > which is being standardized for AArch64, so there will be only > one implementation. Another big portion is DMA-engine support, > which is moving out of arch/arm as soon as we have a proper DT > binding. Finally there are some boilerplate header files that > are going away too. > > Once we're done with this, we will basically need zero code in > arch/*/ to support a new platform, and that is very easy to > share between two distinct arch/* directories ;-)
Ok, arch specific platform code going away completely is a valid solution - if you can pull that off for all new hardware then arch/arm64/ might actually work.
The life time of ARM hw is also a lot shorter than on x86. Plus, given that Apple and MS keeps Linux away from their hardware cryptographically we only have to deal with hw makers who specifically *want* Linux support. A lot of the maintenance pain on x86 comes from the fact that Linux support on a lot of PC hardware is incidental, from the hw maker's POV.
Ok, sounds like a valid plan. Just fix the name please :-)
Thanks,
Ingo
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