On Wed, Apr 04, 2012 at 05:54:13PM +0100, Chris Simmonds wrote: > >Is this a new SoC (no mainline support) or an existing SoC? > > It's a new SoC which will have its own arch/arm/mach-xxx directory
You haven't stated clearly your intention -- is it your first priority to have support for this platform included in Linus' mainline, or are you more interested in the bring-up for a product goal? > >>So my questions are > >>1. Is this a rational approach? > > > >IMHO, you should be developing against mainline, say the last released > >kernel 3.3, if tracking 3.4-rc is too much. And then ask for it to be > >merged via the arm-soc tree if you have no other sub-arch maintainer > >above you. > > It is not feasible to track the tip mainline release both because it > eats up man power in the kernel team but even more so in the QA > team. Probably looking at one kernel release per year, ideally based > on the long term kernel, currently 3.0. Based on your answer, I am guessing the latter option of the two I outlined above. > When it comes to mainlining, is arm-soc the best way? There is no > route via Linaro? That's correct -- the linux-linaro kernel is an integration tree, intended to validate and test cutting edge work happening in both working groups and member SoC and board bring-up. If you want to produce something suitable for mainline, you should base on trunk and uplevel your patches as mainline progresses. In other words, the linux-linaro kernel isn't intended to be a base for /SoC bringup/ efforts [*]; it's much better for you to track trunk and bring in specific branches that you care about. Note that I would certainly not start on 3.0, which is getting old very quickly. If you absolutely care about starting from a "stable" base, then I would start on the latest released kernel (currently 3.3); the state of things in ARM are such that every release you go backwards causes you to miss critical plumbing that we are working on. > >If you need specific features from the Linaro tree, you should use git > >branches to track the tree and cherry-pick the bits that you do need. > >Can you give examples of things that you do need from the Linaro tree? > > Basically, everything in arch/arm/kernel, arch/arm/mm, etc. Right > now the diff is mostly to do with device tree, which is interesting > but not crucial. But the principle is that linux-linaro will have > arm architecture support before mainline, no? Yes, but you shouldn't base your work on linux-linaro, and instead on the topic branches that you care about -- basing your work on a history tree is going to lead to a path of tangled patches that will be much harder to upstream. A manifest of the branches being included in linux-linaro will be available online shortly; I'm waiting for Andrey (copied here) to publish that. [*] The complementary question is what /is/ linux-linaro for, if not to support new SoC bringup. The answer is that it's there to allow people to test cutting edge kernel work on Linaro member platforms -- for instance, if you want to verify how well Device Tree support works on an i.MX53 Quickstart, or how well the latest eMMC 4.5 storage patches work on Exynos. -- Christian Robottom Reis, Engineering VP Brazil (GMT-3) | [+55] 16 9112 6430 | [+1] 612 216 4935 Linaro.org: Open Source Software for ARM SoCs _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
