[OE-core] Very large size of libraries in core-image-minimal rootfs

[Ankur Tyagi]

Hi Khem,

I have no experience with musl but keen to understand does musl
improves/impacts DRAM performance as compared to glibc?

regards
Ankur

On Wed, 27 Nov 2019, 7:17 a.m. Khem Raj, <raj.khem at gmail.com> wrote:

> On Mon, 2019-11-25 at 23:10 +0200, Adrian Bunk wrote:
> > On Mon, Nov 25, 2019 at 07:26:58PM +0000, Ross Burton wrote:
> > > On 25/11/2019 18:37, Ankur Tyagi wrote:
> > > > Hi,
> > > >
> > > > Based upon "thud" branch, I created core-image-minimal for
> > > > am335x-evm
> > > > board and resulting image size is very big(71M)
> > >
> > > If disk size is important then a good first step is to use musl
> > > instead of
> > > glibc:
> > >
> > > TCLIBC = "musl"
> > > ...
> >
> > musl is mainly useful for tiny systems, a 40 MB partition is such a
> > huge
> > amount of space that the size of the C library no longer matters
> > much.
> >
> > The size benefit of replacing glibc with musl is around 2 MB.
>
> I would refrain from labeling as useful for tiny systems. since
> static size is one thing, there is DRAM behaviour which is equally
> important, how malloc and other resource oriented algorithms behave is
> important as well.
>
> secondly, if I have 40MB partition, one might rather want to use extra
> space for implementing features in their product than spend it for
> enabling the system if they can.
>
> there are many other design considerations where musl might make more
> sense
>
> >
> > A partition with an -Os build of Yocto with glibc+systemd (sic)
> > is around 9 MB, together with bootloader and kernel this all
> > fits in a 16 MB flash. Use compression for kernel and root
> > filesystem and everything fits in a 8 MB flash.
> >
>
> -Os is not as well tested option as -O2 is. So we should always
> recommend it with grain of salt, speaking from experience there are
> bugs that will show up with Os which you wont see with O2 and leave a
> bad taste for user
>
> > > Ross
> >
> > cu
> > Adrian
>
> --
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