On Sun, Feb 01, 2015 at 04:38:52PM +0100, Irgendeiner wrote: > >>The latest sunxi kernels perfectly work for Ethernet and SATA > >>(Thanks to everybody who made this happen!!). I do not know enough > >>about the delicate details of Linux kernels, but would be prepared > >>to contribute by what ever needs testing on that platform. > > > >A good first step would be to test whatever boards you have on a > >regular basis (with the current -rc, and ideally linux-next), and > >making sure that everything still works as it used to. And if not, > >report it. > > > >This would be very valuable, and doesn't really require any kernel > >knowledge beside compiling a kernel on your own. > > I have done that for the last few kernels and as said above I did not find > any feature disappearing. So as long as you do not hear from me it works as > expected for BananPi.
Great then :) > The only doubt I have is regarding DMA for Sata, where I am convinced that > already the kernel from Allwinner was faulty. They all show excellent high > speeds for reading from disk and about 3 times slower writing to disk. > Nobody could bring up a convincing reason for this huge factor which imho > should be only a few procent and not > 300%. We're not using the same driver than allwinner was using, so I guess if it shows similar speeds in 3.4 and mainline kernels, the hardware is more to blame. This driver is also used by numerous other SoCs (nvidia, marvell, freescale) that do not show this issue (otherwise, I'm convinced it would have been fixed or at least discussed by now). Since we don't really have any in-depth knowledge of the AHCI controller, I'm not really sure I can suggest a better answer unfortunately. > >>My personal goal is to have a sunxi kernel with Debian Jessie, > >>which lets me bring up an additional point: > >> > >>In some may be not too distant future, the newest sunxi kernel > >>will no longer be compatible with Jessie. What are your opinions > >>and plans to make it possible to use new kernels with then 'old' > >>Jessie? > > > >I'm not aware of that issue. Would you care to expand a bit? > > Debian Jessie is based on the kernel API of v. 3.16. Later kernels also do > work with Jessie as long as this API does not change. So it was no problem > to use kernels 3.17 up to today without any problem, on my test disk I even > have installed them all together (3.16 not fully working). > > Now, if on some probably not too distant day the API gets an incompatible > change, it will no longer be possible to use that kernel with Jessie. > > For platforms like X86 some newer kernels get backports to make them usable > with the the latest version of Debian stable, but for sunxi it will be > problem I do not yet see a solution. First rule of Linux: Do not *ever* break the user-space ABI. It happens, from time to time, but it should (and actually is) considered a bug that needs fixing. So, no matter if you're using x86 or ARM, 3.16 will behave exactly the same from the user-space perspective than a 4.42 kernel. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
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