Messages in this thread | | | Date | Mon, 14 Jul 2014 10:05:35 +0100 | From | Daniel Thompson <> | Subject | Re: [PATCH v7 0/4] arm: Fix DEBUG_LL for multi-platform kernels (without PL01X) |
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On 12/07/14 12:10, Russell King - ARM Linux wrote: > On Sat, Jul 12, 2014 at 11:16:02AM +0100, Russell King - ARM Linux wrote: >> On Mon, Jun 30, 2014 at 12:30:51PM +0100, Daniel Thompson wrote: >>> This patchset removes some single-platform compatibility tricks related >>> to DEBUG_LL and, as a result, allows multi_v7_defconfig derived builds >>> to enable DEBUG_LL. Currently the user selected kbuild setting is >>> ignored and the PL01X's DEBUG_LL stub is silently selected instead. This >>> is a pain if your hardware doesn't have this cell, not least because it >>> takes a little time to figure out that kbuild built the wrong code. >> >> I don't think this is quite right, because I'm now seeing randconfig >> finding build errors with this. We can end up with this configuration: >> >> CONFIG_DEBUG_LL=y >> CONFIG_DEBUG_LL_UART_NONE=y >> # CONFIG_DEBUG_ICEDCC is not set >> # CONFIG_DEBUG_SEMIHOSTING is not set >> # CONFIG_DEBUG_LL_UART_8250 is not set >> # CONFIG_DEBUG_LL_UART_PL01X is not set >> CONFIG_DEBUG_LL_INCLUDE="mach/debug-macro.S" >> # CONFIG_DEBUG_UART_8250 is not set >> >> which results in: >> >> arch/arm/kernel/debug.S:24:33: fatal error: mach/debug-macro.S: No such file or directory >> make[2]: *** [arch/arm/kernel/debug.o] Error 1 >> arch/arm/kernel/head.S:27:33: fatal error: mach/debug-macro.S: No such file or directory >> make[2]: *** [arch/arm/kernel/head.o] Error 1 >> Full config file: >> http://www.arm.linux.org.uk/developer/build/file.php?lid=11023
Thanks. I will look at this.
Problem is that by making the build system honour the user choice we end up breaking the build when the user makes a bad choice (albeit a bad choice that they should not have been given in the first place).
I guess the best fix is to get rid of CONFIG_DEBUG_LL_UART_NONE altogether.
> Note that this also breaks building versatile as an oldconfig. I'll drop > the patch series from my tree for the time being.
There is a difficult problem with oldconfig.
Today DEBUG_LL only works on versatile defconfigs (and oldconfig upgrades from there) because although CONFIG_DEBUG_LL_UART_NONE is selected the build system does not honour this and behaves as though the use selected CONFIG_DEBUG_LL_UART_PL01X instead.
Unfortunately if we fix this and remove CONFIG_DEBUG_LL_UART_NONE as proposed above then the oldconfig will silently select CONFIG_DEBUG_SEMIHOSTING.
In other words I will be able to offer a patch so that oldconfig *compiles* but I don't know how to get it to preserve behaviour (or whether this matters).
Hints about what to do would be very welcome.
Daniel.
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