[yocto] Intel machine with 64 Bit kernel and 32 Bit user space

[Martin Jansa]

It's not as simple as that in some cases, there are some components which
are pulled in 64bit version even when building lib32-foo-image.

Some are easy to override from the config e.g.:
ROOTFS_PKGMANAGE = "${LIB32_PREFIX}opkg"
SPLASH = "${LIB32_PREFIX}psplash"

but to prevent building e.g. syslinux in 64bit version is a bit more tricky.

syslinux.bbclass was fixed long time ago:
commit c8dc421ea18bb7a810501ab6d07efa9c8f6d6eb9
Author: Ming Liu <ming.liu at windriver.com>
Date:   Thu Jun 19 16:42:58 2014 +0800

    syslinux.bbclass: Ensure MLPREFIX is applied to depends flag

    Add MLPREFIX to depends flag to ensure the correct syslinux is
    dependended upon.

-do_bootimg[depends] += "syslinux:do_populate_sysroot \
+do_bootimg[depends] += "${MLPREFIX}syslinux:do_populate_sysroot \

but wic still depends on syslinux without MLPREFIX:

meta/conf/machine/qemux86-64.conf:do_image_wic[depends] +=
"syslinux:do_populate_sysroot syslinux-native:do_populate_sysroot
mtools-native:do_populate_sysroot dosfstools-nat...
meta/conf/machine/qemux86.conf:do_image_wic[depends] +=
"syslinux:do_populate_sysroot syslinux-native:do_populate_sysroot
mtools-native:do_populate_sysroot dosfstools-native...

similarly opkg-utils and some other components are pulled in the
not-prefixed version even when building image with a prefix. I've
eventually got it working with morty (that it was really building only
couple 64bit recipes, mostly kernel and recipes providing external modules
and e.g. depmodwrapper-cross), but it's kind of shaky and error prone, I'll
send fixes for some of these issues, but as we're using morty it's more
complicated to find out what is still needed and what was resolved in newer
OE already.

And there are the issues with allarch recipes mentioned in the other
multilib thread.

Regards,


On Thu, Jul 26, 2018 at 5:59 PM Mark Hatle <mark.hatle at windriver.com> wrote:

> On 7/26/18 10:19 AM, Alexander Kanavin wrote:
> > 2018-07-26 14:56 GMT+02:00 Ayoub Zaki <ayoub.zaki at googlemail.com>:
> >> Is it possible to define a MACHINE configuration with a 64 Bit kernel
> and 32
> >> Bit user space ?
> >>
> >> The user space should not be using a  x32 ABI.
> >
> > I think (but I am not sure), that you can do it with multilib. Define
> > a configuration like this:
> >
> https://github.com/openembedded/openembedded-core/blob/master/meta-skeleton/conf/multilib-example.conf
> >
> > Then build lib32-core-image-minimal. That image should include only 32
> > bit user space, but the kernel will be 64 bit.
>
> Yes this is the typical approach.  Enable multilibs, and then build the
> image
> you you want with the approach multilib prefix.
>
> This works in any multilib configurations, 64-bit, 32-bit, x32, etc..
>
> --Mark
>
> > Alex
> >
>
> --
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