On Tue, Apr 22, 2014 at 01:55:16PM -0400, Nicolas Pitre wrote:
> We do not want people in general to have PLAT_PHYS_OFFSET defined and
> CONFIG_ARM_PATCH_PHYS_VIRT disabled. In fact a huge effort has been
> deployed to go the exact opposite way over the last few years.
>
> There are special cases where CONFIG_ARM_PATCH_PHYS_VIRT needs to be
> turned off for example. But those are specialized configurations and
> they should be the exception not the norm. And you should be knowing
> what you're doing in those cases.
>
> So I doubt it is worth complexifying the linker script for something
> that is meant to be the exception, _especially_ if this is for some
> debugging environment purposes. You may just adjust some setting in
> your environment or do a quick kernel modification locally instead.
> And if you don't know what to modify then you're probably lacking the
> necessary qualifications to perform that kind of kernel debugging in the
> first place.
>
> Making the patch available on a mailing list is fine. If it is useful
> to someone else then it'll be found. But I don't think this is useful
> upstream.
Also, let's not forget that it the ELF file can be modified after the
kernel build:
$ vmlinux=your-vmlinux-file
$ newlma=lma-for-your-platform
$ arm-linux-objcopy $(
arm-linux-objdump -h ${vmlinux} |
grep -B1 'LOAD' | \
sed -nr 's/^[ 0-9]*[0-9] ([^ ]*).*/--change-section-lma \1+${newlma}/p') \
${vmlinux} ${vmlinux}-${newlma}
(It would be nice if objcopy could be told "change any section with _this_
attribute".)
The nice thing about this is that you can keep ARM_PATCH_PHYS_VIRT enabled
and not have to change the code in any way - you just fix up the headers on
the ELF file.
--
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improving, and getting towards what was expected from it.
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