From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36640) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dG7L4-0001GT-50 for qemu-devel@nongnu.org; Wed, 31 May 2017 13:23:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dG7Kz-00065g-Cv for qemu-devel@nongnu.org; Wed, 31 May 2017 13:23:18 -0400 Received: from mail-wm0-x235.google.com ([2a00:1450:400c:c09::235]:34908) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dG7Kz-00064f-4j for qemu-devel@nongnu.org; Wed, 31 May 2017 13:23:13 -0400 Received: by mail-wm0-x235.google.com with SMTP id b84so127456809wmh.0 for ; Wed, 31 May 2017 10:23:13 -0700 (PDT) References: <20170531150933.10156-1-alex.bennee@linaro.org> <20170531150933.10156-3-alex.bennee@linaro.org> <20170531181737.230cbded@p-imbrenda.boeblingen.de.ibm.com> <20170531183324.03bf98fe@bahia.lan> <20170531185106.126f19ac@p-imbrenda.boeblingen.de.ibm.com> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <20170531185106.126f19ac@p-imbrenda.boeblingen.de.ibm.com> Date: Wed, 31 May 2017 18:23:28 +0100 Message-ID: <87shjlrldb.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH v1 2/2] gdbstub: don't fail on vCont; C04:0; c packets List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Claudio Imbrenda Cc: Greg Kurz , pbonzini@redhat.com, doug16k@gmail.com, qemu-devel@nongnu.org Claudio Imbrenda writes: > On Wed, 31 May 2017 18:33:24 +0200 > Greg Kurz wrote: > >> On Wed, 31 May 2017 18:17:37 +0200 >> Claudio Imbrenda wrote: >> >> > On Wed, 31 May 2017 16:09:33 +0100 >> > Alex Bennée wrote: >> > >> > > The thread-id of 0 means any CPU but we then ignore the fact we >> > > find the first_cpu in this case who can have an index of 0. >> > > Instead of bailing out just test if we have managed to match up >> > > thread-id to a CPU. >> > > >> > > Otherwise you get: >> > > gdb_handle_packet: command='vCont;C04:0;c' >> > > put_packet: reply='E22' >> > > >> > > Signed-off-by: Alex Bennée >> > > --- >> > > gdbstub.c | 4 ++-- >> > > 1 file changed, 2 insertions(+), 2 deletions(-) >> > > >> > > diff --git a/gdbstub.c b/gdbstub.c >> > > index a249846954..29c9ed3002 100644 >> > > --- a/gdbstub.c >> > > +++ b/gdbstub.c >> > > @@ -934,8 +934,8 @@ static int gdb_handle_vcont(GDBState *s, const >> > > char *p) >> > > * CPU first, and only then we can use its index. >> > > */ >> > > cpu = find_cpu(idx); >> > > - /* invalid CPU/thread specified */ >> > > - if (!idx || !cpu) { >> > > + /* invalid thread specified, cpu not found. */ >> > > + if (!cpu) { >> > > res = -EINVAL; >> > > goto out; >> > > } >> > >> > This is strange. cpu_index() is defined as: >> > >> > static inline int cpu_index(CPUState *cpu) >> > { >> > #if defined(CONFIG_USER_ONLY) >> > return cpu->host_tid; >> > #else >> > return cpu->cpu_index + 1; >> > #endif >> > } >> > >> > therefore it shouldn't return 0 under any circumstance, and >> >> I think it is 0 for first_cpu in user mode. > > in linux-user/syscall.c: > > info->tid = gettid(); > cpu->host_tid = info->tid; > > kernel thread-ids are system-wide unique and can't be 0 This only applies to newly cloned threads. The first is unset. > >> > find_cpu(idx) should also fail if idx == 0, because internally it >> > also uses cpu_index() >> > >> > on the other hand, you say that the patch does fix the problem for >> > you, which really confuses me. >> > >> > >> > >> > (probably) completely unrelatedly, this: >> > >> > res = qemu_strtoul(p + 1, &p, 16, &tmp); >> > >> > should be like this instead: >> > >> > res = qemu_strtoul(p, &p, 16, &tmp); >> > >> > but this shouldn't impact you in any way. >> > >> > >> > >> -- Alex Bennée