Messages in this thread | | | Date | Fri, 2 Dec 2011 10:21:24 +0100 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] arm: add default value for PHYS_OFFSET Kconfig setting |
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Hello Nicolas,
On Fri, Dec 02, 2011 at 12:33:26AM -0500, Nicolas Pitre wrote: > On Fri, 2 Dec 2011, Nicolas Pitre wrote: > > > On Thu, 1 Dec 2011, Paul Gortmaker wrote: > > > > > On Thu, Dec 1, 2011 at 9:19 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > > > On Thursday 01 December 2011, Paul Gortmaker wrote: > > > >> Commit 1b9f95f8ade9efc2bd49f0e7b9dc61a038ac3eef introduced the new > > > >> Kconfig for PHYS_OFFSET but it did not specify a default value. > > > >> > > > >> This has the undesired side effect of breaking an implictly used > > > >> trick for updating defconfigs on the fly for routine buildtesting > > > >> across all arch and all platforms, i.e. > > > >> > > > >> cp /path/to/somedefconfig .config ; yes "" | make oldconfig > > > >> > > > > > > > > FWIW, a better way to achieve the above is using > > > > > > > > make KCONFIG_ALLCONFIG=/path/to/somedefconfig listnewconfig alldefconfig > > > > > > > > which does not have this problem. > > > > > > > > Your patch looks still ok, but you might want to update your scripts > > > > to be more robust. > > > > > > Thanks -- but on the other hand, the above use case does actually > > > emulate exactly what happens when someone runs the > > > "make oldconfig" and simply holds down the Enter key. (yes it > > > happens probably way more than we want to know...) > > > > > > So, I guess what I'm trying to say is that the above "script" is > > > intentionally fragile. :) As a use case, we shouldn't break it. > > > > Well... I took a while before replying because I'm also modifying things > > around this, but those changes are good for a merge window not a -rc > > period. > > > > Still, I don't think your patch is good, even as a temporary measure. > > The fact is that we can't just pick a random default value since it is > > likely to be wrong for the majority of the boards as the right answer > > for this option is quite varied. So the fact that the config system > > insists on your entering a proper value is actually a good thing. > > > > In the at91x40_defconfig case, it has CONFIG_EMBEDDED=y. If it was not > > selected then you'd get CONFIG_ARM_PATCH_PHYS_VIRT=y by default and then > > no CONFIG_PHYS_OFFSET would be presented. > > > > So the right fix here would actually consist of adding to > > at91x40_defconfig either CONFIG_ARM_PATCH_PHYS_VIRT=y, or a default > > value for CONFIG_PHYS_OFFSET which is the right value for that platform. > > And it seems that at91x40 is the only defconfig with MMU=n, so the only > option is really to provide a default CONFIG_PHYS_OFFSET. So what about > this: > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index e084b7e981..a24672924f 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -222,6 +222,7 @@ config NEED_MACH_MEMORY_H > config PHYS_OFFSET > hex "Physical address of main memory" > depends on !ARM_PATCH_PHYS_VIRT && !NEED_MACH_MEMORY_H > + default DRAM_BASE if !MMU > help > Please provide the physical address corresponding to the > location of main memory in your system. > > Eventually the DRAM_BASE config option could simply be replaced by > PHYS_OFFSET directly, but that's a larger change. I'm working on a MMU-less machine, too and had that change already in my working copy. I was about to commit and it send out later today.
So: Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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