[OpenWrt-Devel] [LEDE-DEV] [PATCH] include/kernel: Do not strip kernel's Elf

Felix Fietkau nbd at nbd.name
Wed May 18 09:49:46 EDT 2016

On 2016-05-18 15:06, Alexey Brodkin wrote:
> Hi Felix,
> On Wed, 2016-05-18 at 14:57 +0200, Felix Fietkau wrote:
>> On 2016-05-16 16:42, Alexey Brodkin wrote:
>> > 
>> > If an image gets built as an Elf there's a chance
>> > it will be used by developers for debugging purposes.
>> > In that case it's very helpful to keep debugging info
>> > in that image.
>> > 
>> > I would think that most OWRT-powered devices in production
>> > will use some form of binary image for booting so Elf
>> > flavours could be left a bit bulkier with more debug info
>> > inside.
>> > 
>> > Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>
>> You can get the bulky one directly from the kernel source directory, and
>> there is definitely some value in having stripped ELF binaries as well
>> for devices that can load them.
> Well indeed in kernel's source directory we have an unstripped elf.
> But what happens at least in case of ARC we build only one kernel's elf
> and then as a post-built step we patch in .dtb for all boards we build OWRT.
> In other words in "bin/arc770-uClibc" folder I have:
>  1) openwrt-arc770-generic-axs101-initramfs.elf
>  2) openwrt-arc770-generic-nsim_700-initramfs.elf
> Both are stripped but work as they are on the corresponding boards.
> In "build_dir/target-arc_arc700_uClibc-1.0.9/linux-arc770_generic/linux-4.4.7/"
> I have perfectly unstripped vmlinux but it won't work on either board because of
> missing device tree blob.
> That means if one wants to get image for a board X with debug symbols he or she
> will need to do manual patching in of .dtb. Which is not the most convenient thing ever.
It's a lot simpler than that: You can boot the stripped and patched elf
image from bin/ and use the vmlinux from the kernel source for the
debugger afterwards. They are fully compatible.

- Felix
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