From: Masami Hiramatsu <mhiramat@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Frank Rowand <frowand.list@gmail.com>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
devicetree@vger.kernel.org
Subject: Re: [RFC PATCH 00/11] tracing: of: Boot time tracing using devicetree
Date: Tue, 2 Jul 2019 18:47:30 +0900 [thread overview]
Message-ID: <20190702184730.b0247eb780ffa48d40a61a81@kernel.org> (raw)
In-Reply-To: <20190627195817.211ab4bea422f37e539e47e8@kernel.org>
Hello,
On Thu, 27 Jun 2019 19:58:17 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Hi Rob,
>
> On Wed, 26 Jun 2019 15:58:50 -0600
> Rob Herring <robh+dt@kernel.org> wrote:
>
> > On Fri, Jun 21, 2019 at 10:18 AM Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > >
> > > Hi,
> > >
> > > Here is an RFC series of patches to add boot-time tracing using
> > > devicetree.
> > >
> > > Currently, kernel support boot-time tracing using kernel command-line
> > > parameters. But that is very limited because of limited expressions
> > > and limited length of command line. Recently, useful features like
> > > histogram, synthetic events, etc. are being added to ftrace, but it is
> > > clear that we can not expand command-line options to support these
> > > features.
> > >
> > > Hoever, I've found that there is a devicetree which can pass more
> > > structured commands to kernel at boot time :) The devicetree is usually
> > > used for dscribing hardware configuration, but I think we can expand it
> > > for software configuration too (e.g. AOSP and OPTEE already introduced
> > > firmware node.) Also, grub and qemu already supports loading devicetree,
> > > so we can use it not only on embedded devices but also on x86 PC too.
> >
> > Do the x86 versions of grub, qemu, EFI, any other bootloader actually
> > enable DT support? I didn't think so. Certainly, an x86 kernel doesn't
> > normally (other than OLPC and ce4100) have a defined way to even pass
> > a dtb from the bootloader to the kernel and the kernel doesn't
> > unflatten the dtb.
>
> Sorry, the grub part, I just found this entry. I need to check this
> can work on x86 too.
I've confirmed that grub-x86 doesn't support devicetree option. I tried
to add it, and tested it.
https://github.com/mhiramat/grub/commit/644c35bfd2d18c772cc353b74215344f8264923a
This works if there is ACPI, if it includes /chosen/linux,ftrace node only.
(Anyway, we don't need other nodes on x86)
At this moment, grub doesn't support DT overlay, so on arm/arm64 user must
decompile DTB, add linux,ftrace node for tracing and compile it again.
But if it supports overlay, I think we can give an overlay for tracer setting
on boot up, that will be handy on arm/arm64 too. :)
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
prev parent reply other threads:[~2019-07-02 9:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-21 16:18 [RFC PATCH 00/11] tracing: of: Boot time tracing using devicetree Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 01/11] tracing: Apply soft-disabled and filter to tracepoints printk Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 02/11] tracing: kprobes: Output kprobe event to printk buffer Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 03/11] tracing: Expose EXPORT_SYMBOL_GPL symbol Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 04/11] tracing: kprobes: Register to dynevent earlier stage Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 05/11] tracing: Accept different type for synthetic event fields Masami Hiramatsu
2019-06-21 16:18 ` [RFC PATCH 06/11] tracing: Add NULL trace-array check in print_synth_event() Masami Hiramatsu
2019-06-21 16:19 ` [RFC PATCH 07/11] dt-bindings: tracing: Add ftrace binding document Masami Hiramatsu
2019-06-21 16:19 ` [RFC PATCH 08/11] tracing: of: Add setup tracing by devicetree support Masami Hiramatsu
2019-06-21 16:19 ` [RFC PATCH 09/11] tracing: of: Add trace event settings Masami Hiramatsu
2019-06-21 16:19 ` [RFC PATCH 10/11] tracing: of: Add kprobe event support Masami Hiramatsu
2019-06-21 16:19 ` [RFC PATCH 11/11] tracing: of: Add synthetic " Masami Hiramatsu
2019-06-23 19:58 ` [RFC PATCH 00/11] tracing: of: Boot time tracing using devicetree Frank Rowand
2019-06-24 2:52 ` Masami Hiramatsu
2019-06-24 22:31 ` Frank Rowand
2019-06-25 5:00 ` Masami Hiramatsu
2019-07-15 13:55 ` Frank Rowand
2019-07-17 0:57 ` Masami Hiramatsu
2019-06-26 21:58 ` Rob Herring
2019-06-27 2:55 ` Frank Rowand
2019-06-27 10:58 ` Masami Hiramatsu
2019-07-02 9:47 ` Masami Hiramatsu [this message]
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