[arch-general] kernel full compilation ?

[Alexander Kapshuk]

On Tue, Mar 3, 2020 at 3:30 PM Pascal via arch-general
<arch-general at archlinux.org> wrote:
>
> yes, I've just recompiled and this second time was much faster !
>
> to be more precise, here is the very small modification made to the file
> mentioned above :
>
> --- src/linux-5.4.23/block/blk-core.c 2020-02-28 17:22:29.000000000 +0100
> +++ /tmp/blk-core.c 2020-03-03 14:25:56.049803851 +0100
> @@ -799,7 +799,7 @@
>   "to read-only block-device %s (partno %d)\n",
>   bio_devname(bio, b), part->partno);
>   /* Older lvm-tools actually trigger this */
> - return false;
> + return true;
>   }
>
>   return false;
>
> Le mar. 3 mars 2020 à 14:19, Caleb Maclennan <caleb at alerque.com> a écrit :
>
> > On Tue, Mar 3, 2020 at 4:06 PM Pascal via arch-general <
> > arch-general at archlinux.org> wrote:
> >
> >> it's necessary to recompile completely even if the kernel I'm using is the
> >> same as the one I want to apply a small modification on ?
> >>
> >
> > Yes.
> >
> > The only small consolation is that once you compile it once and have a
> > source tree that has been fully built on your system, further small changes
> > and re-compiles will go much faster because it will figure out _some_ of
> > the things it doesn't need to do again. I the case of the kernel, it still
> > won't be fast.
> >
> > Caleb
> >

You could just do:
make M=block ;to rebuild the part of the kernel modified
make ;to rebuild all other object files affected and to relink the kernel image

from the root of your kernel source tree, followed by:
make modules_install
make install
etc

See http://files.kroah.com/lkn/lkn_pdf/ch04.pdf, Building Only a
Portion of the Kernel.