On 07/24/12 11:53, Arnd Bergmann wrote: > On Tuesday 24 July 2012, Catalin Marinas wrote: >> On Mon, Jul 23, 2012 at 09:52:22PM +0100, Christopher Covington wrote: >>> Hi Catalin and Stephen, >>> >>> Catalin Marinas - July 8, 2012, 9:18 a.m. >>>> On Fri, Jul 06, 2012 at 10:32:54PM +0100, Stephen Warren wrote: >>>> >>>>> Also, on Tegra at least and perhaps OMAP too, there are a few parts >>>>> of earlyprintk serial port setup (i.e. port selection) which happen >>>>> as part of the decompressor rather than the main kernel image, so >>>>> we'd have to re-jig that too. >>>> >>>> Whatever we did on AArch32, if it was useful and we want to follow a >>>> similar model it needs porting given that the code cannot be shared. So >>>> there is nothing to re-jig but rather implement. >>>> >>>> As for earlyprintk, you can initialise it in the decompressed kernel >>>> anyway. But even though it's a useful debugging tool, it goes against >>>> the single Image aim (at least the current printascii/addruart >>>> implementation). I don't have a proper implementation yet. >>> >>> Would DCC [1] be a reasonably commonly available early printk mechanism >>> for the single image to provide? >> >> Yes, this can be implemented but I think it has its own restrictions, >> requiring a JTAG connection. > > Right, which means that it's not generic and we still need to make > a decision for a how we want to solve the underlying problem. The > options I see are: > > 1. Have no earlyprintk before loading the console drivers > 2. Make the series from Domenico architecture independent code > 3. Reimplement a layer like that, differently > 4. Make it a compile-time option and allow this only for > low level debugging purposes but disable it in distro kernels.
I have found earlyprintk to be very valuable for debugging the many times that boot fails for me. Not having earlyprintk does not seem a good idea to me. Option 4 is perfectly acceptable for my use cases. -Frank -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
