From: Carlos O'Donell <codonell@redhat.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>,
nd@arm.com, GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] Reserve static TLS for dynamically loaded initial-exec TLS only [BZ #25051]
Date: Thu, 20 Feb 2020 10:05:06 -0500 [thread overview]
Message-ID: <043f4682-d009-0365-9bdc-f9bd402683b5@redhat.com> (raw)
In-Reply-To: <87k14lmcct.fsf@oldenburg2.str.redhat.com>
On 2/17/20 11:01 AM, Florian Weimer wrote:
> * Carlos O'Donell:
>
>> Let me take a stab at this:
>>
>> (1) File a bug to indicate all libraries must stop using
>> TLS IE to fix dlmopen issues with TLS IE.
>
> Do you mean glibc components, or do you view this as a distribution-wide
> change?
All glibc libraries should stop using TLS IE and we should file bugs for
fixing these instances where TLS IE was used to work around startup ordering
problems.
I did not intend to imply a distribution-wide policy. Other packages can do
what they want, and their use of TLS IE will limit dlmopen capabilities
including causing it to fail.
>> (2) Set DL_NNS to 4, and add a tunable that lets you change
>> the limit to reduce surplus memory allocated.
>>
>> (2.a) send linux man-pages a patch to make dlmopen(3)
>> ambiguous about how many namespaces are supported and
>> to point at the tunable to increase the memory used.
>>
>> (3) I think that the surplus should be split into two
>> blocks:
>> (3.a) Some reserved for TLS IE libs.
>> (3.b) Some reserved for tlsdesc optimization.
>>
>> My opinion is that any library that is loaded and
>> needs TLS IE should be able to use (3.a). We should
>> reserve enough for (3.a) to be able to load glibc
>> libraries, libgomp, and libgl (as you note).
>
> There's also a potential for not letting audit libraries consume
> namespace slots (once they are dynamic). This will enable lower DL_NNS
> defaults.
I don't quite follow what you mean here, can you expand on that?
--
Cheers,
Carlos.
next prev parent reply other threads:[~2020-02-20 15:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 11:54 [PATCH] Reserve static TLS for dynamically loaded initial-exec TLS only [BZ #25051] Szabolcs Nagy
2020-01-07 12:09 ` Florian Weimer
2020-01-07 12:50 ` Szabolcs Nagy
2020-02-13 16:38 ` Szabolcs Nagy
2020-02-13 18:07 ` Carlos O'Donell
2020-02-17 16:01 ` Florian Weimer
2020-02-20 15:05 ` Carlos O'Donell [this message]
2020-02-21 12:58 ` Florian Weimer
2020-02-27 16:21 ` Szabolcs Nagy
2020-02-27 16:31 ` Florian Weimer
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