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Re: [PATCHv2] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
- From: Torvald Riegel <triegel at redhat dot com>
- To: munroesj at linux dot vnet dot ibm dot com
- Cc: "Carlos O'Donell" <carlos at redhat dot com>, Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>, GNU C Library <libc-alpha at sourceware dot org>, "Steven J. Munroe" <sjmunroe at us dot ibm dot com>, Tulio Machado <tuliom at linux dot vnet dot ibm dot com>
- Date: Thu, 27 Aug 2015 22:26:06 +0200
- Subject: Re: [PATCHv2] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB
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- References: <C6F0963E-DA8E-48B3-B6F6-8D6A4C399AED at linux dot vnet dot ibm dot com> <55DE2452 dot 1000907 at redhat dot com> <1440643271 dot 31963 dot 17 dot camel at oc7878010663> <1440643752 dot 3213 dot 4 dot camel at oc7878010663> <55DF11D0 dot 2090100 at redhat dot com> <1440706010 dot 11409 dot 14 dot camel at oc7878010663>
On Thu, 2015-08-27 at 15:06 -0500, Steven Munroe wrote:
> QED a Clone syscall is effectively a full barrier (Sequentially
> Consistent) between stores in the thread parent and loads in the thread
> child.
Note that it would have to affect stores in the child too (ie, child
stores overwrite parent stores that happened before the syscall), and
loads in the parent shouldn't be able to read from stores in the child
either.
I guess that's the case because the OS should execute a full barrier on
syscalls, and will use an acquire barrier or similar after getting the
OK to start a new thread and before actually executing the thread?