From: Richard Henderson <rth@twiddle.net>
To: David Munday <cromom@soe.ucsc.edu>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] NPTL user mode fixes
Date: Wed, 28 Apr 2010 11:56:44 -0700 [thread overview]
Message-ID: <4BD884EC.3060403@twiddle.net> (raw)
In-Reply-To: <015e01cae594$3de6d920$b9b48b60$@ucsc.edu>
On 04/26/2010 04:00 PM, David Munday wrote:
> I starting to work with qemu to enable NPTL dependent binaries to run in
> user mode. I see that currently NPTL is not supported for SPARC or x86.
>
> What is still left to do for NPTL support?
The thing that's missing to enable the compile with NPTL is cpu_set_tls.
For Sparc I believe this is merely an assignment to %g7. For x86, you
need to arrange for a call to do_set_thread_area, which is currently
private to linux-user/syscall.c.
However, the other thing that will need to be fixed is that neither port
implements its atomic operations atomically -- the implementations merely
assume that only one thread is active. See do_store_exclusive in
linux-user/main.c for how several ports handle their atomic operations.
It'll be a bit different for Sparc singe it has LDSTUB and SWAP as well
as CAS. It'll be lots different for x86, since quite a few read-modify-write
operations can be made atomic by use of the LOCK prefix (this could be
quite an undertaking, actually).
r~
prev parent reply other threads:[~2010-04-28 19:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-26 23:00 [Qemu-devel] NPTL user mode fixes David Munday
2010-04-27 18:01 ` Blue Swirl
2010-04-28 18:56 ` Richard Henderson [this message]
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