Date: Mon, 21 Aug 2023 11:30:21 +0200 From: Felix Palmen <zirias@freebsd.org> To: ports@freebsd.org, emulation@freebsd.org Subject: Re: Building a Linuxulator userland from source Message-ID: <ycunrmdtcbpudkpvklm4mty2udi2jlx75akpfc3qfpi7xhwx65@ln4asxaakt3n> In-Reply-To: <SI2PR01MB50365D850421F63522B5269DFA1EA@SI2PR01MB5036.apcprd01.prod.exchangelabs.com> References: <xcztahm3vu3bjghjqqxuoy2xabyjmyfq22jw6mkaaaqo7wa36s@fdq7dlvpuhlk> <i3kr2kukjwgw2xvjlzgshwe72bjpnln4lvl7prhk77nelzidm6@2g56zi3ku7ec> <SI2PR01MB5036EAB6EE2D224BBDAF86B0FA19A@SI2PR01MB5036.apcprd01.prod.exchangelabs.com> <SI2PR01MB50366A01896746D4DAFC18F7FA1EA@SI2PR01MB5036.apcprd01.prod.exchangelabs.com> <cnbxytnfqoh4dr6clz3qdhygeehjh7e3kqjdiarhiqsjhburhk@eotxvli5ma23> <SI2PR01MB50365D850421F63522B5269DFA1EA@SI2PR01MB5036.apcprd01.prod.exchangelabs.com>
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* Tatsuki Makino <tatsuki_makino@hotmail.com> [20230821 17:40]:
> Felix Palmen wrote on 2023/08/21 16:21:
> > This works perfectly fine when used from within a Linux shell. Example
> > from testing my new userland:
> >=20
> > | [00:00:20] Entering interactive test mode. Type 'exit' when done.
> > | root@14a-default:~ # /compat/linux/bin/bash
> > | bash-5.2# ldd /bin/bash
> > | linux-vdso.so.1 (0x00007fffffffe000)
> > | libreadline.so.8 =3D> /usr/lib64/libreadline.so.8 (0x00000008=
01154000)
> > | libhistory.so.8 =3D> /usr/lib64/libhistory.so.8 (0x0000000801=
1ad000)
> > | libncursesw.so.6 =3D> /usr/lib64/libncursesw.so.6 (0x00000008=
011bb000)
> > | libc.so.6 =3D> /usr/lib64/libc.so.6 (0x0000000801400000)
> > | /lib64/ld-linux-x86-64.so.2 (0x0000000001021000)
> > | bash-5.2#=20
>=20
> Oh, I understand.
> If we try to use it directly, the command not found if bash is not instal=
led.
Installing a FreeBSD bash won't help either, this script expects
/bin/bash which will never exist on FreeBSD (it's installed in
/usr/local/bin/bash).
> we want poudriere to mount real devfs to /compat/linux/dev as well,
> since linux binary behaves like chroot to /compat/linux.
Well, first /compat/linux is *not* a chroot or jail, but actually just
some kind of "filesystem overlay", which is the great thing about it. It
means Linux binaries can access *all* files of the FreeBSD system, as
long as they are not "shadowed" by something below /compat/linux.
And indeed, to support building native Linux software using poudriere,
it *should* mount devfs on /compat/linux/dev.
> Alternatively, pkg-plist in emulators/linux_base-c7 is creating dummy
> /compat/linux/dev, and removing it seems to be a workaround.
In a live system, there's no issue. /etc/rc.d/linux will mount all
necessary pseudo filesystems:
| if checkyesno linux_mounts_enable; then
| linux_mount linprocfs "${_emul_path}/proc" -o nocover
| linux_mount linsysfs "${_emul_path}/sys" -o nocover
| linux_mount devfs "${_emul_path}/dev" -o nocover
| linux_mount fdescfs "${_emul_path}/dev/fd" -o nocover,linrdlnk
| linux_mount tmpfs "${_emul_path}/dev/shm" -o nocover,mode=3D1777
| fi
So far, poudriere doesn't mount anything on /compat/linux/dev for its
building jails, although it *does* mount /compat/linux/proc.
For now, I found that a simple symlink to the real /dev also does the
trick, which I can add with some hackery in the port Makefile itself, by
adding some extra prerequisite for "build-depends" when a poudriere
build is detected. In the long run, poudriere should mount a real devfs
though.
Cheers, Felix
--=20
Felix Palmen <zirias@FreeBSD.org> {private} felix@palmen-it.de
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