From: Joseph Myers <josmyers@redhat.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Carlos O'Donell <carlos@redhat.com>,
Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
gcc@gcc.gnu.org, libc-alpha@sourceware.org,
Iain Sandoe <iain@sandoe.co.uk>,
aburgess@redhat.com, lttng-dev@lists.lttng.org
Subject: Re: New TLS usage in libgcc_s.so.1, compatibility impact
Date: Mon, 15 Jan 2024 16:29:02 +0000 (UTC) [thread overview]
Message-ID: <7c159449-acb9-3448-1829-1cd26ec2c60@redhat.com> (raw)
In-Reply-To: <87jzoa6249.fsf@oldenburg.str.redhat.com>
On Mon, 15 Jan 2024, Florian Weimer via Gcc wrote:
> The change conflated multiple issues: sanitizer support,
> async-signal-safe TLS access, and eager allocation of all TLS-related
> memory, so that subsequent accesses cannot fail. My impression was the
> main point of contention was eager allocation because it was perceived
> as a breaking semantic change. Nowadays, as long as we are willing to
> maintain both allocator variants, we could offer a choice between them
> controlled by a tunable. For sanitizer compatibility, we could perform
> eager allocation using malloc. It's probably a good idea to do it this
> way anyway because a separate mmap-based allocator would increase TLB
> pressure.
Related to eager allocation is the question of whether libgcc_s.so.1
should be loaded unconditionally by glibc at startup - doing so has much
the same motivation (avoiding subsequent failures from interfaces that
don't have any good way to signal failure, when glibc currently loads
libgcc_s.so.1 dynamically), but also no doubt compatibility risk.
--
Joseph S. Myers
josmyers@redhat.com
next prev parent reply other threads:[~2024-01-15 16:29 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-13 12:49 Florian Weimer
2024-01-15 12:46 ` Szabolcs Nagy
2024-01-15 13:55 ` Adhemerval Zanella Netto
2024-01-15 14:47 ` Carlos O'Donell
2024-01-15 15:35 ` Florian Weimer
2024-01-15 15:38 ` Iain Sandoe
2024-01-15 16:44 ` Florian Weimer
2024-01-15 16:29 ` Joseph Myers [this message]
2024-01-15 19:05 ` [lttng-dev] " Mathieu Desnoyers
2024-01-15 19:42 ` Florian Weimer
2024-01-15 20:08 ` Mathieu Desnoyers
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