Re: ppc64le vmlinuz is huge when building with BTF

[Eduard Zingerman <eddyz87@gmail.com>]

On Thu, 2023-06-15 at 18:15 +0300, Eduard Zingerman wrote:
> On Thu, 2023-06-15 at 12:32 +0900, Dominique Martinet wrote:
> > Hi,
> > 
> > coming from alpine: https://gitlab.alpinelinux.org/alpine/aports/-/issues/12563
> > 
> > alice noticed the kernel packages got quite bigger, in particular for
> > ppc64le I've confirmed that the vmlinuz file size jump when building
> > with BTF:
> > currently released package with BTF:
> > https://dl-cdn.alpinelinux.org/alpine/edge/main/ppc64le/linux-lts-6.1.33-r0.apk
> > 272M	boot/vmlinuz-lts
> 
> Hi Dominique,
> 
> I've just checked the linked apk and it looks like DWARF sections are
> not stripped and take most of the space, e.g.:
> 
> $ llvm-objdump --headers boot/vmlinuz-lts | grep \.debug \
>   | gawk '{ sum += strtonum("0x"$3); } END { print sum; }' | numfmt --to iec
> 228M
> 
> Compare this to BTF sections size:
> 
> $ llvm-objdump --headers boot/vmlinuz-lts | grep BTF \
>   | gawk '{ sum += strtonum("0x"$3); } END { print sum; }' | numfmt --to iec
> 3,9M

Heh, Alan answered while I was looking into it, sorry for the spam.

> 
> > 
> > test build without BTF:
> > https://gitlab.alpinelinux.org/martinetd/aports/-/jobs/1049335
> > 44M	boot/vmlinuz-lts
> > 
> > 
> > Is that a known issue?
> > We'll probably just turn off BTF for the ppc64le build for now, but it
> > might be worth checking.
> > 
> > 
> > While I have your attention, even the x86_64 package grew much bigger
> > than I thought it would, the installed modules directory go from 90MB to
> > 108MB gzipped); it's a 18% increase (including kernel: 103->122MB) which
> > is more than what I'd expect out of BTF.
> > Most users don't care about BTF so it'd be great if they could be built
> > and installed separately (debug package all over again..) or limiting
> > the growth a bit more if possible.
> > I haven't tried yet but at this point ikheaders is probably worth
> > considering instead..
> > Perhaps we're missing some stripping option or something?
> > 
> > 
> > Thanks!
>