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Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig
From: |
Russell King - ARM Linux |
Subject: |
Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig |
Date: |
Tue, 22 Apr 2014 19:36:39 +0100 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
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.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, (continued)
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Jason Gunthorpe, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Jason Gunthorpe, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Arnd Bergmann, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Arnd Bergmann, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Daniel Thompson, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Jason Gunthorpe, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Nicolas Pitre, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig,
Russell King - ARM Linux <=
Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Rob Herring, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Nicolas Pitre, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Rob Herring, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Rob Herring, 2014/04/17
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Nicolas Pitre, 2014/04/18
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Daniel Thompson, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Russell King - ARM Linux, 2014/04/22
- Re: [Qemu-devel] Change of TEXT_OFFSET for multi_v7_defconfig, Daniel Thompson, 2014/04/22