From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E850390205 for ; Sat, 3 Oct 2026 19:20:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791055205; cv=none; b=mwis91npGSp5Pgf7a+jrOtAWp1vw4Ic6kVkb35fw/mKe/tAE6kwbMoJxJ7e/CYd3/B2EnF4r1c7lanJz+pHLZ8icyc5XeYTWCYNWh7nWW28fgBulK/7DtMaVQX7nPRVe2OozKCYk7UH4dYpAKCqPrSq3pUu/SnNM1grpg4Q3pS4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791055205; c=relaxed/simple; bh=lQC/tzUXPUFWV7ATFp0IrLxd6rPKg89wd2TRwDOA5Xs=; h=From:To:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=O/JZjhvXlFvwPoMRvFoI8lKzLKd7DZ32I02Mw9Km4b0BH74hlqpxi7fSQmQcelewQnxgzJWhRV0gHSgqIZqtcev0bWYkPwqAsdAYo4wnqbhR1JBh2Prh6b+TxFJRhV4apdXEhSrnTB9CMDk4vrWqpAKqyC2K0Mxhb4oFuRxmoYo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=1GMvZdEf; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Z9RooACT; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="1GMvZdEf"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Z9RooACT" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1791055195; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=shRUBfjxsCqyUdcPcY0vYnPceFVTdw8WbE/8YyUhAGs=; b=1GMvZdEfgA/ABMPrhysmkU48H2yw03tDIYuv32m06lHuu6H9oKrEibtWv9Nzwlbiq+aW51 Ep0PIO9c1WMLnZKlW5JG4aG+O4mXvdjKvst0y3Hz9zfWL6N/slqKCkUaeUncqnlKFpNBeg Ge5zxeVBk4IIZ2E/ZOB2+0XCy0pPsfGkK1nFtJ232cw9tSrXEc574pP4WPxSd9o20DJafA aqZaVAZkWMsnQHXc0CfbOPdedOhbSDioCmw6XW0m6lAKVmsS1P74aJKdM4t4A4CGVcT/C0 dGw7mfmoH+KX1PRFJeolv+UTfIUToOIWtintT9pwHge7qvmPDyJIHR3ls7dLcQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1791055195; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=shRUBfjxsCqyUdcPcY0vYnPceFVTdw8WbE/8YyUhAGs=; b=Z9RooACTKIF/AAABPZVKVqEZaPiDR60YliIWHScSVdGaUy4ONrUv5TkcbvvsuAGCLzLcvf QOehPV75y7ceA8CQ== To: debarbos@redhat.com, williams@redhat.com, vkuznets@redhat.com, linux-rt-users@vger.kernel.org, Petr Mladek Subject: Re: Console Hang on SMP Secondary CPU Bringup In-Reply-To: References: <87fqytbhmx.fsf@jogness.linutronix.de> Date: Sat, 03 Oct 2026 21:25:55 +0206 Message-ID: <87se2mlhgk.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On 2026-10-02, Derek Barbosa wrote: >> To be sure it is timing related due to the nbcon atomic printing, you >> could try short-circuiting: >> >> drivers/tty/serial/8250/8250_port.c:serial8250_console_write_atomic() >> >> so that it immediately does >> >> return true; >> > > I will be running more trials of the reproducer to confirm, but so > far, we still hang. I wasn't able to extract some traces, hopefully > will be able to soon... That is surprising. For the v6.6-rt you can manually add: #define CONFIG_SERIAL_8250_LEGACY_CONSOLE to drivers/tty/serial/8250/8250.h and this should cause the driver to run in legacy mode. If you add this macro to 8250.h, does the hang go away? > FWIW, Clark suggested it may be worth setting keep_bootcon in the > commandline. If you use keep_bootcon, then the 8250 will operate in a special mode that is compatible with the bootcons. It is not a solution, even if it worked. > I'm off to LPC, so I will be radio silent for another day or two while > I have these spin on the Azure VMs. Sebastian and I are also off to LPC, so we can continue the discussion in person. :-) John