From: eggonlea@gmail.com (Li Li)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] arm: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6
Date: Fri, 8 Apr 2011 22:40:12 +0800 [thread overview]
Message-ID: <BANLkTimEzTk2CCVRZMcR_jmWJGkvm1vvdQ@mail.gmail.com> (raw)
In-Reply-To: <20110408143541.GU26912@shareable.org>
Ah, I see. That's why I saw abnormal behavior when I enabled TLS EMU
on an ARMv7 SMP SOC. Many thanks! :)
On Fri, Apr 8, 2011 at 10:35 PM, Jamie Lokier <jamie@shareable.org> wrote:
> Li Li wrote:
>> Nicolas,
>>
>> Thanks for the explanation. :)
>>
>> I noticed what you mentioned. Actually, Kconfig says TLS EMU might be
>> used in some "old" (e.g. pre-armv6) SMP platforms without TLS
>> register. In such a case, could we still ensure it's SMP safe by a
>> single ldr?
>
> In that case, the hardware TLS 'mcr' is used, which traps and is
> emulated by the undefined instruction handler. ?It's not fast but
> presumably those platforms don't really matter.
>
> See CONFIG_TLS_REG_EMUL in arch/arm/kernel/traps.c, and 'tls_emu'.
>
> 'tls_emu' is a constant, so if a kernel built for TLS emulation is run
> on something which has the TLS register, it will not work properly.
>
> -- JAmie
>
next prev parent reply other threads:[~2011-04-08 14:40 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-21 13:51 [PATCH 0/2] Make ARMv6 behave with TLS, VFPv3, and NEON Tony Lindgren
2010-06-21 13:51 ` [PATCH 1/2] arm: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6 Tony Lindgren
2010-06-22 9:28 ` Tony Lindgren
2010-06-22 17:00 ` Jamie Lokier
2010-06-23 7:39 ` Tony Lindgren
2010-06-23 8:12 ` Russell King - ARM Linux
2010-06-23 9:28 ` Tony Lindgren
2010-06-23 9:32 ` Russell King - ARM Linux
2010-06-23 13:28 ` Jamie Lokier
2010-06-23 13:36 ` Jamie Lokier
2010-06-23 14:19 ` Nicolas Pitre
2010-06-24 0:28 ` Jamie Lokier
2010-06-29 14:18 ` Tony Lindgren
2010-06-29 19:20 ` Nicolas Pitre
2010-06-30 11:08 ` Tony Lindgren
2010-06-30 13:17 ` Tony Lindgren
2010-06-30 14:42 ` Nicolas Pitre
2010-07-01 9:25 ` Tony Lindgren
2010-07-01 17:40 ` Jamie Lokier
2010-07-02 2:37 ` Nicolas Pitre
2010-07-02 10:37 ` Tony Lindgren
2010-07-05 13:55 ` Tony Lindgren
2011-04-08 3:39 ` Li Li
2011-04-08 13:19 ` Nicolas Pitre
2011-04-08 13:35 ` Li Li
2011-04-08 14:35 ` Jamie Lokier
2011-04-08 14:40 ` Li Li [this message]
2010-06-21 13:51 ` [PATCH 2/2] arm: Make VFPv3 usable on ARMv6 Tony Lindgren
2010-06-22 12:59 ` Catalin Marinas
2010-06-22 13:20 ` Tony Lindgren
2010-06-23 7:57 ` Tony Lindgren
2010-06-25 13:50 ` Catalin Marinas
2010-07-01 12:42 ` Tony Lindgren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=BANLkTimEzTk2CCVRZMcR_jmWJGkvm1vvdQ@mail.gmail.com \
--to=eggonlea@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).