Workaround for QSBR mode issue #4390

[Ondřej Surý]

Well, if the device has broken membarrier() it has more problems than just broken dig.

I would say that fixing liburcu to not use membarrier() on that particular platform would have
been a better fix than using unsupported QSBR for BIND 9. But it is your call...

Ondrej
--
Ondřej Surý (He/Him)
ondrej at isc.org

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> On 26. 8. 2026, at 09:41, Robert Kirkman via bind-users <bind-users at lists.isc.org> wrote:
> 
> August 26, 2026 at 2:25 AM, "Petr Špaček" <pspacek at isc.org> wrote:
> On 26. 08. 26 3:00, Robert Kirkman via bind-users wrote:
> Hello, we have developed this workaround for the hanging problem with builds of bind with the configure argument --with-liburcu=qsbr :
> the hanging problem is reproducible on both ARM Android and ARM GNU/Linux, and is fixed on both by this.
> Out of curiosity, why do you want QSBR?
> 
> -- Petr Špaček
> 
> Thanks for asking. In 2025, we received a report that the dig command had the "Bad system call" error immediately on the device Huawei LLD-L21 with Android 9until the QSBR mode was enabled, which worked around the problem.
> 
> https://github.com/termux/termux-packages/issues/23820
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