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Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only fo
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now) |
Date: |
Wed, 26 Oct 2011 17:02:56 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-10-26 16:54, Peter Maydell wrote:
> On 26 October 2011 15:39, Paolo Bonzini <address@hidden> wrote:
>> On 10/26/2011 04:03 PM, Peter Maydell wrote:
>>>
>>> For the record (since I think we only talked about this on IRC):
>>> * the POSIX TLS fallback code doesn't work on Linux hosts for
>>> linux-user emulation (the constructor is never called to set up
>>> the TLS for the main thread, probably something to do with our
>>> custom linker script, since it does work OK for system emulation)
>>> * if I recall correctly from IRC it doesn't compile on OpenBSD
>>>
>>> so for 1.0 perhaps we need to fall back to a simpler set of patches
>>> that just avoid the regression in thread support for linux-user ?
>>
>> I agree.
>
> I was thinking something like a trivial qemu-tls.h which does
>
> #ifdef __linux__
> #define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
> #define DEFINE_TLS(type, x) __thread __typeof__(type) tls__##x
> #define get_tls(x) tls__##x
> #else
> /* Dummy implementations -- we can get away with this because system
> * mode is effectively single-threaded for our current limited use of
> * TLS, and the only -user mode which supports multiple threads is
> * linux-user.
We will use it in system mode as well, e.g. when I'll push away the
global lock from KVM entry/exits. So let's state that it is only
interesting on Linux hosts for now.
Otherwise, this looks good.
Jan
> * TODO: proper implementations via Win32 .tls sections and
> * POSIX pthread_getspecific.
> */
> #define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
> #define DEFINE_TLS(type, x) __typeof__(type) tls__##x
> #define get_tls(x) tls__##x
> #endif
>
> and then we can just use your "Make cpu_single_env thread-local"
> patch as-is:
>
> http://git.linaro.org/gitweb?p=people/pmaydell/qemu-arm.git;a=commitdiff;h=b674559fc8a67ae7d30fe3ab3062d5855ac77d2d
>
> (for that matter we could apply the "Prepare Windows port for
> thread-local cpu_single_env" patch too, but that's not a requirement.)
>
> -- PMM
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), (continued)
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Jan Kiszka, 2011/10/04
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Paolo Bonzini, 2011/10/05
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Jan Kiszka, 2011/10/05
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Paolo Bonzini, 2011/10/05
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), David Gilbert, 2011/10/07
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Paolo Bonzini, 2011/10/08
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Peter Maydell, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Paolo Bonzini, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Peter Maydell, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Paolo Bonzini, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now),
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Peter Maydell, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Jan Kiszka, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Peter Maydell, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Jan Kiszka, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Andreas Färber, 2011/10/26
- Re: [Qemu-devel] [PATCH] Make cpu_single_env thread local (Linux only for now), Jan Kiszka, 2011/10/26