Date: Fri, 31 Dec 2021 18:20:46 -0800 From: Mark Millard via freebsd-current <freebsd-current@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: Dimitry Andric <dim@FreeBSD.org>, Ed Maste <emaste@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@FreeBSD.org> Subject: Re: git: 5e6a2d6eb220 - main - Reapply: move libc++ from /usr/lib to /lib [add /usr/lib/libc++.so.1 -> ../../lib/libc++.so.1 ?] Message-ID: <4FEBC148-25FA-4BDB-BFD3-FDBE8D093B9C@yahoo.com> In-Reply-To: <595C5A0E-B024-46EE-883E-2FCA6ADFE171@yahoo.com> References: <45118DB4-F8C4-4F96-9CAA-5DC5DCFFEB7E@yahoo.com> <3140C5F6-495F-441C-AA6B-542F3BC53B62@yahoo.com> <5F8AF0B2-3AF3-4BE4-B5D1-9030F2605FFD@yahoo.com> <EDD53581-B5FA-4D52-9F9A-AAB1DA1974D2@yahoo.com> <5a24eb16-078f-15c5-dcd4-ecef33d15ac7@FreeBSD.org> <03AF30DA-A632-4223-908C-9F5250D82079@yahoo.com> <76FC7AFB-DA78-4A44-BC74-4477C9E11413@yahoo.com> <f5d458c2-fa12-8893-47b4-001716a3416b@FreeBSD.org> <82BE340A-321C-43F3-AD7B-2E8466ADA17F@yahoo.com> <595C5A0E-B024-46EE-883E-2FCA6ADFE171@yahoo.com>
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On 2021-Dec-31, at 18:18, Mark Millard <marklmi@yahoo.com> wrote:
> On 2021-Dec-31, at 17:46, Mark Millard <marklmi@yahoo.com> wrote:
>=20
>> On 2021-Dec-31, at 15:04, John Baldwin <jhb@freebsd.org> wrote:
>>=20
>>> On 12/31/21 2:59 PM, Mark Millard wrote:
>>>> On 2021-Dec-31, at 14:28, Mark Millard <marklmi@yahoo.com> wrote:
>>>>> On 2021-Dec-30, at 14:04, John Baldwin <jhb@freebsd.org> wrote:
>>>>>=20
>>>>>> On 12/30/21 1:09 PM, Mark Millard wrote:
>>>>>>> On 2021-Dec-30, at 13:05, Mark Millard <marklmi@yahoo.com> =
wrote:
>>>>>>>> This asks a question in a different direction that my prior
>>>>>>>> reports about my builds vs. Cy's reported build.
>>>>>>>>=20
>>>>>>>> Background:
>>>>>>>>=20
>>>>>>>> =
/usr/obj/BUILDs/main-amd64-nodbg-clang/usr/main-src/amd64.amd64/tmp/usr/li=
b/libc++.so:GROUP ( /lib/libc++.so.1 /usr/lib/libcxxrt.so
>>>>>>>> and:
>>>>>>>> lrwxr-xr-x 1 root wheel 23 Dec 29 13:17:01 2021 =
/usr/lib/libcxxrt.so -> ../../lib/libcxxrt.so.1
>>>>>>>>=20
>>>>>>>> Why did libc++.so.1 not get a:
>>>>>>>>=20
>>>>>>>> /usr/lib/libc++.so.1 -> ../../lib/libc++.so.1
>>>>>>> I forgot to remove the .1 on the left hand side:
>>>>>>> /usr/lib/libc++.so -> ../../lib/libc++.so.1
>>>>>>=20
>>>>>> Because for libc++.so we don't just symlink to the current =
version of the library
>>>>>> (as we do for most other shared libraries) to tell the compiler =
what to link against
>>>>>> for -lc++, instead we use a linker script that tells the compiler =
to link against
>>>>>> both of those libraries when -lc++ is encountered.
>>>>>=20
>>>>> A better identification of what looks odd to me is the
>>>>> path variations in:
>>>>>=20
>>>>> # more /usr/lib/libc++.so
>>>> Another not great day on my part: That path alone makes
>>>> the mix of /lib/ and /usr/lib/ use involved, given the
>>>> reference to /lib/libc++.so.1 . That would still be true
>>>> if the other path had been /lib/libcxxrt.so .
>>>=20
>>> /usr/lib/libc++.so is only used by the compiler/linker when linking =
a binary.
>>> The resulting binary has the associated paths (/lib/libc++.so.1 and
>>> /usr/lib/libcxxrt.so.1) in its DT_NEEDED. So it is fine for the .so =
to be
>>> in /usr/lib. This is the same with /usr/lib/libc.so vs =
/lib/libc.so.7.
>>>=20
>>> However, your point about libcxxrt.so.1 is valid. It needs to also =
be moved
>>> to /lib if libc++.so.1 is moved to /lib. Doing so will also require =
yet another
>>> depend-clean.sh fixup (well, probably just adjusting the one I added =
to
>>> check the libcxxrt path instead of libc++ path).
>>=20
>> Hmm. Looking (now after having updated so /lib/libc++.so.1
>> is in use, not that this is any different here):
>>=20
>> # ls -Tld /lib/libcxx* /usr/lib/libcxx*
>> -r--r--r-- 1 root wheel 131656 Dec 31 14:19:49 2021 =
/lib/libcxxrt.so.1
>> -r--r--r-- 1 root wheel 355764 Dec 24 15:19:42 2021 =
/usr/lib/libcxxrt.a
>> lrwxr-xr-x 1 root wheel 23 Dec 31 14:19:49 2021 =
/usr/lib/libcxxrt.so -> ../../lib/libcxxrt.so.1
>>=20
>> # more /usr/lib/libc++.so=20
>> /* $FreeBSD$ */
>> GROUP ( /lib/libc++.so.1 /usr/lib/libcxxrt.so )
>>=20
>> So: no actual reference to /usr/lib/libcxxrt.so.1 but
>> a reference in the DT_NEEDED to /usr/lib/libcxxrt.so ?
>>=20
>> May be just /usr/lib/libc++.so needs different text in order
>> for DT_NEEDED to have different text related to libcxxrt in
>> future build activities, avoiding /usr/lib/ ?
>>=20
>>=20
>> For reference:
>>=20
>> # uname -apKU
>> FreeBSD amd64_ZFS 14.0-CURRENT FreeBSD 14.0-CURRENT #27 =
main-n252090-5650d340ad66-dirty: Fri Dec 31 06:00:41 PST 2021 =
root@amd64_ZFS:/usr/obj/BUILDs/main-amd64-nodbg-clang/usr/main-src/amd64.a=
md64/sys/GENERIC-NODBG amd64 amd64 1400046 1400046
>>=20
>=20
> In a aarch64 context I looked at an old executable via ldd -a :
>=20
> # ldd -a bt
> /usr/home/root/c_tests/bt:
> libexecinfo.so.1 =3D> /usr/lib/libexecinfo.so.1 (0x41c19000)
> libc++.so.1 =3D> /lib/libc++.so.1 (0x42484000)
> libcxxrt.so.1 =3D> /lib/libcxxrt.so.1 (0x43038000)
> libm.so.5 =3D> /lib/libm.so.5 (0x44a4c000)
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /usr/lib/libexecinfo.so.1:
> libelf.so.2 =3D> /lib/libelf.so.2 (0x4581e000)
> libgcc_s.so.1 =3D> /lib/libgcc_s.so.1 (0x46e4f000)
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /lib/libc++.so.1:
> libcxxrt.so.1 =3D> /lib/libcxxrt.so.1 (0x43038000)
> libgcc_s.so.1 =3D> /lib/libgcc_s.so.1 (0x46e4f000)
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /lib/libcxxrt.so.1:
> libgcc_s.so.1 =3D> /lib/libgcc_s.so.1 (0x46e4f000)
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /lib/libm.so.5:
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /lib/libelf.so.2:
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
> /lib/libgcc_s.so.1:
> libc.so.7 =3D> /lib/libc.so.7 (0x439ce000)
>=20
> Looks like something already deals with finding
> /lib/libcxxrt.so.1 . But it is not obvious what
> path it started with and how much processing was
> done (or when) to end up with /lib/libc++.so.1
> showing.
>=20
> But there is still a /usr/lib/ reference overall:
>=20
> /usr/lib/libexecinfo.so.1
>=20
> But this is because the old program turned out to
> be an old experiment:
>=20
> # more bt.c=20
> // bt.c
> // from releng/12 (12.2?) context (pre-llvm12), but not releng/13 :
> // # cc -o bt bt.c -lexecinfo
> // # ./bt
> // Rerun in llvm12 context, such as main after the switch: crash.
>=20
> #include <execinfo.h>
> int main() {
> void *addrlist[100];
> backtrace(addrlist, 100);
> }
>=20
> Although, for some reason, the executable was dated
> 2021-Jul-15, not that I remember why I'd rebuilt it
> then.
>=20
> # file bt
> bt: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), =
dynamically linked, interpreter /libexec/ld-elf.so.1, for FreeBSD 14.0 =
(1400025), FreeBSD-style, with debug_info, not stripped
>=20
> nm -a bt shows:
That should have referenced: elfdump -a bt | more
> entry: 0
> d_tag: DT_NEEDED
> d_val: libexecinfo.so.1
>=20
> None of the DT_NEEDED entries had paths shown.
>=20
> The only /usr/lib/ reference was:
>=20
> entry: 65
> st_name: /usr/lib/crti.o
> st_value: 0
> st_size: 0
> st_info: STT_FILE STB_LOCAL
> st_shndx: 65521
>=20
> Overall: backtrace requires /usr/lib/ accessibility
> for main-n252090-5650d340ad66 in order to access
> /usr/lib/libexecinfo.so.1 .
>=20
> For reference:
>=20
> # uname -apKU
> FreeBSD CA72_16Gp_ZFS 14.0-CURRENT FreeBSD 14.0-CURRENT #34 =
main-n252090-5650d340ad66-dirty: Fri Dec 31 06:30:22 PST 2021 =
root@CA72_16Gp_ZFS:/usr/obj/BUILDs/main-CA72-nodbg-clang/usr/main-src/arm6=
4.aarch64/sys/GENERIC-NODBG-CA72 arm64 aarch64 1400046 1400046
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
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