Date: Fri, 31 Dec 2021 18:18:56 -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: <595C5A0E-B024-46EE-883E-2FCA6ADFE171@yahoo.com> In-Reply-To: <82BE340A-321C-43F3-AD7B-2E8466ADA17F@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>
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On 2021-Dec-31, at 17:46, Mark Millard <marklmi@yahoo.com> wrote:
> On 2021-Dec-31, at 15:04, John Baldwin <jhb@freebsd.org> wrote:
>
>> 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:
>>>>
>>>>> 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.
>>>>>>>
>>>>>>> Background:
>>>>>>>
>>>>>>> /usr/obj/BUILDs/main-amd64-nodbg-clang/usr/main-src/amd64.amd64/tmp/usr/lib/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
>>>>>>>
>>>>>>> Why did libc++.so.1 not get a:
>>>>>>>
>>>>>>> /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
>>>>>
>>>>> 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.
>>>>
>>>> A better identification of what looks odd to me is the
>>>> path variations in:
>>>>
>>>> # 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 .
>>
>> /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.
>>
>> 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).
>
> Hmm. Looking (now after having updated so /lib/libc++.so.1
> is in use, not that this is any different here):
>
> # 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
>
> # more /usr/lib/libc++.so
> /* $FreeBSD$ */
> GROUP ( /lib/libc++.so.1 /usr/lib/libcxxrt.so )
>
> So: no actual reference to /usr/lib/libcxxrt.so.1 but
> a reference in the DT_NEEDED to /usr/lib/libcxxrt.so ?
>
> 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/ ?
>
>
> For reference:
>
> # 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.amd64/sys/GENERIC-NODBG amd64 amd64 1400046 1400046
>
In a aarch64 context I looked at an old executable via ldd -a :
# ldd -a bt
/usr/home/root/c_tests/bt:
libexecinfo.so.1 => /usr/lib/libexecinfo.so.1 (0x41c19000)
libc++.so.1 => /lib/libc++.so.1 (0x42484000)
libcxxrt.so.1 => /lib/libcxxrt.so.1 (0x43038000)
libm.so.5 => /lib/libm.so.5 (0x44a4c000)
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/usr/lib/libexecinfo.so.1:
libelf.so.2 => /lib/libelf.so.2 (0x4581e000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x46e4f000)
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/lib/libc++.so.1:
libcxxrt.so.1 => /lib/libcxxrt.so.1 (0x43038000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x46e4f000)
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/lib/libcxxrt.so.1:
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x46e4f000)
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/lib/libm.so.5:
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/lib/libelf.so.2:
libc.so.7 => /lib/libc.so.7 (0x439ce000)
/lib/libgcc_s.so.1:
libc.so.7 => /lib/libc.so.7 (0x439ce000)
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.
But there is still a /usr/lib/ reference overall:
/usr/lib/libexecinfo.so.1
But this is because the old program turned out to
be an old experiment:
# more bt.c
// 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.
#include <execinfo.h>
int main() {
void *addrlist[100];
backtrace(addrlist, 100);
}
Although, for some reason, the executable was dated
2021-Jul-15, not that I remember why I'd rebuilt it
then.
# 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
nm -a bt shows:
entry: 0
d_tag: DT_NEEDED
d_val: libexecinfo.so.1
None of the DT_NEEDED entries had paths shown.
The only /usr/lib/ reference was:
entry: 65
st_name: /usr/lib/crti.o
st_value: 0
st_size: 0
st_info: STT_FILE STB_LOCAL
st_shndx: 65521
Overall: backtrace requires /usr/lib/ accessibility
for main-n252090-5650d340ad66 in order to access
/usr/lib/libexecinfo.so.1 .
For reference:
# 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/arm64.aarch64/sys/GENERIC-NODBG-CA72 arm64 aarch64 1400046 1400046
===
Mark Millard
marklmi at yahoo.com
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