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Date: Wed, 31 May 2017 19:06:29 +0200
From: Greg Kurz <groug@kaod.org>
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Subject: Re: [Qemu-devel] [PATCH v1 2/2] gdbstub: don't fail on vCont; C04:0;
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To: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Cc: Alex =?UTF-8?B?QmVubsOpZQ==?= <alex.bennee@linaro.org>, pbonzini@redhat.com, doug16k@gmail.com, qemu-devel@nongnu.org

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On Wed, 31 May 2017 18:51:06 +0200
Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> wrote:
[...]
> > >=20
> > > This is strange. cpu_index() is defined as:
> > >=20
> > > static inline int cpu_index(CPUState *cpu)
> > > {
> > > #if defined(CONFIG_USER_ONLY)
> > >     return cpu->host_tid;
> > > #else
> > >     return cpu->cpu_index + 1;
> > > #endif
> > > }
> > >=20
> > > therefore it shouldn't return 0 under any circumstance, and   =20
> >=20
> > I think it is 0 for first_cpu in user mode. =20
>=20
> in linux-user/syscall.c:
>=20
> info->tid =3D gettid();
> cpu->host_tid =3D info->tid;
>=20
> kernel thread-ids are system-wide unique and can't be 0
> =20

This is correct but these lines are in clone_func(). This gets called for
all threads but the "main" thread which I believe to be associated to
first_cpu.

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