From: Will Deacon <will.deacon@arm.com>
To: Timur Tabi <timur@codeaurora.org>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Shanker Donthineni <shankerd@codeaurora.org>,
"awallis@codeaurora.org" <awallis@codeaurora.org>,
"abhimany@codeaurora.org" <abhimany@codeaurora.org>,
"sboyd@codeaurora.org" <sboyd@codeaurora.org>,
Vipul Gandhi <vgandhi@codeaurora.org>
Subject: Re: [PATCH 1/3] hvc_dcc: bind driver to core0 for reads and writes
Date: Tue, 30 Jun 2015 14:58:15 +0100 [thread overview]
Message-ID: <20150630135815.GK27725@arm.com> (raw)
In-Reply-To: <1435344756-20901-1-git-send-email-timur@codeaurora.org>
On Fri, Jun 26, 2015 at 07:52:34PM +0100, Timur Tabi wrote:
> Some debuggers, such as Trace32 from Lauterbach GmbH, do not handle
> reads/writes from/to DCC on secondary cores. Each core has its
> own DCC device registers, so when a core reads or writes from/to DCC,
> it only accesses its own DCC device. Since kernel code can run on
> any core, every time the kernel wants to write to the console, it
> might write to a different DCC.
>
> In SMP mode, Trace32 only uses the DCC on core 0. In AMP mode, it
> creates multiple windows, and each window shows the DCC output
> only from that core's DCC. The result is that console output is
> either lost or scattered across windows.
>
> Selecting this option will enable code that serializes all console
> input and output to core 0. The DCC driver will create input and
> output FIFOs that all cores will use. Reads and writes from/to DCC
> are handled by a workqueue that runs only core 0.
What happens if CPU0 is hotplugged off?
Will
next prev parent reply other threads:[~2015-06-30 13:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-26 18:52 [PATCH 1/3] hvc_dcc: bind driver to core0 for reads and writes Timur Tabi
2015-06-26 18:52 ` [PATCH 2/3] hvc_dcc: don't ignore errors during initialization Timur Tabi
2015-06-26 18:52 ` [PATCH 3/3] [v2] ARM64: TTY: hvc_dcc: Add support for ARM64 dcc Timur Tabi
2015-06-26 19:28 ` [PATCH 1/3] hvc_dcc: bind driver to core0 for reads and writes Timur Tabi
2015-06-30 13:58 ` Will Deacon [this message]
2015-06-30 14:07 ` Timur Tabi
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