On Friday 01 April 2011 23:10:04 Kevin Hilman wrote: > Arnd Bergmann <arnd@xxxxxxxx> writes: > > > On Friday 01 April 2011, Detlef Vollmann wrote: > >> On 04/01/11 15:54, Arnd Bergmann wrote: > > > >> > 9. All interesting work is going into a handful of platforms, all of which > >> > are ARMv7 based. > >> Define interesting. > > > > The ones that are causing the churn that we're talking about. > > Platforms that have been working forever and only need to get > > the occasional bug fix are boring, i.e. not the problem. > > I'm not sure I follow the ARMv7-only thinking either. > > Picking ARMv7 only would be a good way to avoid part of the problem, but > IMO, it doesn't really address the root causes. Part of the ugliness of > the platform-specific hackery (and the "churn" to clean some of it up) > is precisely due to support for multiple ARM architecture versions, and > the various SoCs in a family that use them. For example, linux-omap > supports OMAP1 (ARMv5), OMAP2 (ARMv6), OMAP3 (ARMv7) and OMAP4 (ARMv7 > SMP), and OMAP2/3/4 in a single binary. > > Also, since we've only very recently got to the point of being able to > support ARMv6 + ARMv7 UP & SMP in the same kernel, making a decision now > that only ARMv7 is important seems like a step backwards. If the > ultimate goal is getting to a point where we have infrastrucure that can > be cross-SoC, surely this same infrastrucure should support multiple ARM > architecture revisions. Yes, forget about the ARMv7 part of my proposal, that was not a main point. If we decide to have a new clean platform variant the way I suggested, it would be nice to support all machines in a single kernel binary, and at least v6+v7 is a solved problem. Supporting a second kernel binary up to v5 with the same source is also simple, as would be big-endian/little-endian variants, or thumb2/arm variants. We might not want to do all combinations from the start though, and I would choose ARMv6/v7-thumb2-le simply because that's what Linaro is focusing on. The idea is to start with a clearly defined set, but write the code in a way that makes it possible to extend in other directions. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
