Ubuntu 18.04 on ARM64: undefined reference to `exp@GLIBC_2.29'

[Benoit Blanchon]

Hi,

I originally sent this question to the PDFium mailing list and was told to post it here.

I successfully compiled a shared library of PDFium on Ubuntu 20.04 with "target_cpu" set to either "x86", "x64", "arm", or "arm64"

(see https://github.com/bblanchon/pdfium-binaries)

However, if I try to do the same with Ubuntu 18.04, all targets build, except "arm64".

The link step fails with the following errors:

libpdfium.so: undefined reference to `exp@GLIBC_2.29'
libpdfium.so: undefined reference to `log@GLIBC_2.29'
libpdfium.so: undefined reference to `pow@GLIBC_2.29'

I investigated the problem and reported my conclusions here:

https://github.com/bblanchon/pdfium-binaries/issues/82#issuecomment-1160190986

In short, "reversion_glibc.py", the script that changes the required glibc version in the sysroot, is skipped for arm64. The comment says "Glibc is compiled in a way where many libm math functions do not have compatibility symbols for versions <= 2.17."

This comment suggests that we can't target Ubuntu 18.04 on ARM64, but I'd like to know if there is a workaround.

Please let me know if you have any information that could help.

Best regards,

Benoit Blanchon

[geisserml]

@Chromium Developers: Any feedback on this?
A project of mine that uses pdfium-binaries recently got an issue report because the minimum required glibc version is too high on ARM64 (see https://github.com/pypdfium2-team/pypdfium2/issues/165).

[Lei Zhang]

This issue recently got resolved in https://crrev.com/1084974, and
PDFium will pick up that change in the very near future.

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[Egor Pasko]

On Tue, Jan 3, 2023 at 4:26 PM geisserml <geis...@gmail.com> wrote:

@Chromium Developers: Any feedback on this?
A project of mine that uses pdfium-binaries recently got an issue report because the minimum required glibc version is too high on ARM64 (see https://github.com/pypdfium2-team/pypdfium2/issues/165).

 I guess as a workaround you can try building PDFium on an ARM64 machine running Ubuntu 18.04. Perhaps this would require some tweaks to sysroot setup, just to take system libraries without modification.

On Wednesday, July 6, 2022 at 7:47:51 PM UTC+2 benoit....@gmail.com wrote:

Hi,

I originally sent this question to the PDFium mailing list and was told to post it here.

I successfully compiled a shared library of PDFium on Ubuntu 20.04 with "target_cpu" set to either "x86", "x64", "arm", or "arm64"

(see https://github.com/bblanchon/pdfium-binaries)

However, if I try to do the same with Ubuntu 18.04, all targets build, except "arm64".

The link step fails with the following errors:

libpdfium.so: undefined reference to `exp@GLIBC_2.29'
libpdfium.so: undefined reference to `log@GLIBC_2.29'
libpdfium.so: undefined reference to `pow@GLIBC_2.29'

I investigated the problem and reported my conclusions here:

https://github.com/bblanchon/pdfium-binaries/issues/82#issuecomment-1160190986

In short, "reversion_glibc.py", the script that changes the required glibc version in the sysroot, is skipped for arm64. The comment says "Glibc is compiled in a way where many libm math functions do not have compatibility symbols for versions <= 2.17."

This comment suggests that we can't target Ubuntu 18.04 on ARM64, but I'd like to know if there is a workaround.

Please let me know if you have any information that could help.

Best regards,

Benoit Blanchon

[geisserml]

That's great news, thanks!

[Lei Zhang]

Yes. It shouldn't be a problem for Ubuntu 18.04, which ships with glibc 2.27.

On Wed, Jan 4, 2023 at 11:51 AM geisserml <geis...@gmail.com> wrote:
>
> The description of https://crrev.com/1084974 says "the glibc version requirement has been bumped to 2.26" - does this apply to PDFium as well?

[geisserml]

The description of https://crrev.com/1084974 says "the glibc version requirement has been bumped to 2.26" - does this apply to PDFium as well?

On Wednesday, January 4, 2023 at 6:31:38 PM UTC+1 geisserml wrote:

[geisserml]

(note for readers: the previous two messages are in wrong order for some reason)

[geisserml]

Confusingly enough, the latest pdfium-binaries build (5692) still runs on my Debian 9 armhf device with glibc 2.24 .
How is that possible if pdfium is supposed to require glibc >= 2.26 ?

[Lei Zhang]

Since Chromium/PDFium folks are not the ones building the
pdfium-binaries you are referring to, we don't have an exact answer.

When crrev.com/1084974 bumped up the glibc requirement, it means
binaries built with that sysroot can potentially require glibc 2.26.
To be safe, that is the listed requirement. The actual requirement for
any given binary can be lower. e.g. Running `objdump -p
path/to/pdfium_test` in my local developer build shows only GLIBC_2.25
in the Version References section. But there's no guarantee and it can
be bumped up to 2.26 at any time.

[geisserml]

Thank you! Since pdfium-binaries use the official build tooling, I think it will be that sysroot.