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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [for-next][PATCH 04/26] bootconfig: Add Extra Boot Config support
Date: Wed, 19 Feb 2020 11:26:32 +0900	[thread overview]
Message-ID: <20200219112632.ca2b7f683271a6864eb68149@kernel.org> (raw)
In-Reply-To: <20200218132724.GC14449@zn.tnic>

On Tue, 18 Feb 2020 14:27:24 +0100
Borislav Petkov <bp@alien8.de> wrote:

> On Tue, Feb 11, 2020 at 11:02:07AM +0900, Masami Hiramatsu wrote:
> > Sorry, you might misunderstand that the bootconfig replaces legacy command
> > line. No, the legacy command line is still there and at least the part of
> > suppremental command line parts of bootconfig are merged into the command
> > line and shown in dmesg. So even if the user use bootconfig, their kernel
> > command line was just updated, they can grub it and simply paste on other
> > machine (if it accepts longer command line)
> 
> Ok, I did just play with the thing. I used this boot config for my guest:
> 
> ---
> kernel {
> 	root=/dev/sda1
> 	resume=/dev/sda2
> 	debug
> 	ignore_loglevel
> 	log_buf_len=16M
> 	earlyprintk=ttyS0,115200
> 	console=ttyS0,115200

Ah, bootconfig syntax interprets the "," as a delimiter of array elements.
So those must be quoted by "" (or '') as below.

	earlyprintk="ttyS0,115200"
	console="ttyS0,115200"

> 	console=tty0

Oops, I forgot to support double parameters.

> 	no_console_suspend
> }
> 
> init {
> 	net.ifnames=0
> }
> ---
> 
> and added it to an initrd which I created especially for this. Which
> brings me to the next issue I see: AFAIU, bootconfig requires people
> to have initrd. And the majority of deployments do have initrd enabled
> but there are use cases where people don't need it. So if bootconfig is
> going to be default Y, it better support that case.

Yes, I think we can embed bootconfig into the kernel image while
building it as a text data. I think appending the bootconfig to kernel
image will be hard because some kernel image will be compressed and self-
extracted on memory. It might break original data.

> For example and for a similar reason I support builtin microcode in the
> microcode loader - when you don't want to enable initrd.

Thanks for the good information! I'll check it.

> Then, I did add the above bootconfig to the initrd:
> 
> ./tools/bootconfig/bootconfig -a bootconfig /tmp/initrd.img
> Apply bootconfig to /tmp/initrd.img
>         Number of nodes: 21
>         Size: 194 bytes
>         Checksum: 16268
> 
> and booted my guest.
> 
> The thing I noticed is that the guest doesn't show any output in its
> window anymore but only shows the login window when it is done booting.
> 
> And that is probably because of the console= thing. /proc/bootconfig has
> 
> $ cat /proc/bootconfig
> kernel.root = "/dev/sda1"
> kernel.resume = "/dev/sda2"
> kernel.debug = ""
> kernel.ignore_loglevel = ""
> kernel.log_buf_len = "16M"
> kernel.earlyprintk = "ttyS0", "115200"
> kernel.console = "ttyS0", "115200", "tty0"
> kernel.no_console_suspend = ""
> init.net.ifnames = "0"
> 
> and bootconfig parsing has merged the console= parameters. And the same
> thing happens if I boot the guest with "console=ttyS0,115200,tty0" on
> the normal cmdline. But
> 
> console=ttyS0,115200 console=tty0
> 
> is not the same as
> 
> console=ttyS0,115200,tty0

Yes, that is my mistake. Since the legacy command line doesn't support
array, it should be expanded. If you write it correctly, I will ensure
it to
console=ttyS0,115200 console=tty0

> 
> Former has been this way since forever if you wanna have serial output
> to ttyS* *and* tty output at the same time.
> 
> Also, I wouldn't want to rule out any other changes in behavior in
> other command line options due to this change in parsing and merging of
> options.

For the above example, I can fix it. I also would not like to change the
behaviors. Could you share your concerning items if you have more?

> 
> So again, I'm still not convinced bootconfig should be used everywhere
> and by default.
> 
> In addition to the initrd requirement, it needs a special tool to glue
> it to the end of the initrd. Yeah yeah, it is part of the kernel and the
> glueing can be made part of the initrd creation tool but still, it is
> one more and new step.
> 
> Now, if bootconfig can *supplement* the normal command line so that you
> can add more complex configuration directives with it, in *addition* to
> the normal command line, then sure, by all means.
> 
> And it seems that it does that: I did
> 
> ---
> kernel {
>         initcall_debug
> }
> 
> init {
> }
> ---
> 
> and added it to the cmdline:
> 
> [    0.047358] Kernel command line: initcall_debug root=/dev/sda1 resume=/dev/sda2 debug ignore_loglevel log_buf_len=16M earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0 no_console_suspend net.ifnames=0  bootconfig
> 
> and you can see "initcall_debug" there and it did enable the initcall
> debugging output so yeah, that seems to work.
> 
> Btw, if you remove the boot config with the tool (-d) and still boot
> with "bootconfig" it says:
> 
> [    0.043958] bootconfig size -23483140 greater than max size 32767
> 
> so you need to check presence of bootconfig blob and limits in the
> parsing code too or so.

Agreed, that's confusing message.

> 
> In any case, this is only my opinion, of course, and I might very well
> be missing something.

Thank you very much for your opinion and information!
That's very helpful to me.

Thank you,

-- 
Masami Hiramatsu <mhiramat@kernel.org>

  parent reply	other threads:[~2020-02-19  2:26 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-14 21:03 [for-next][PATCH 00/26] tracing: Updates for 5.6 Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 01/26] perf: Make struct ring_buffer less ambiguous Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 02/26] tracing: Rename trace_buffer to array_buffer Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 03/26] tracing: Make struct ring_buffer less ambiguous Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 04/26] bootconfig: Add Extra Boot Config support Steven Rostedt
2020-02-06 11:54   ` Borislav Petkov
2020-02-06 14:41     ` Masami Hiramatsu
2020-02-06 17:20       ` Geert Uytterhoeven
2020-02-07  0:30         ` Masami Hiramatsu
2020-02-07  8:49           ` Geert Uytterhoeven
2020-02-07 13:17             ` Masami Hiramatsu
2020-02-07 14:28               ` [PATCH] bootconfig: Allocate xbc_nodes array dynamically Masami Hiramatsu
2020-02-06 17:58       ` [for-next][PATCH 04/26] bootconfig: Add Extra Boot Config support Borislav Petkov
2020-02-06 18:10         ` Randy Dunlap
2020-02-06 22:39           ` Steven Rostedt
2020-02-06 22:51             ` Borislav Petkov
2020-02-07  8:59             ` Geert Uytterhoeven
2020-02-07  2:46         ` Masami Hiramatsu
2020-02-07 11:41           ` Borislav Petkov
2020-02-07 15:06             ` Masami Hiramatsu
2020-02-10 11:25               ` Borislav Petkov
2020-02-10 15:10                 ` Masami Hiramatsu
2020-02-10 17:40                   ` Borislav Petkov
2020-02-11  2:02                     ` Masami Hiramatsu
2020-02-18 13:27                       ` Borislav Petkov
2020-02-18 17:57                         ` Steven Rostedt
2020-02-18 19:38                           ` Borislav Petkov
2020-02-19  2:26                             ` Masami Hiramatsu
2020-02-19  2:26                           ` Masami Hiramatsu
2020-02-19  2:26                         ` Masami Hiramatsu [this message]
2020-02-11  9:25                     ` Geert Uytterhoeven
2020-01-14 21:03 ` [for-next][PATCH 05/26] bootconfig: Load boot config from the tail of initrd Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 06/26] tools: bootconfig: Add bootconfig command Steven Rostedt
2020-02-07 13:02   ` Michael Ellerman
2020-02-07 13:39     ` Masami Hiramatsu
2020-02-07 13:55     ` [PATCH] tools/bootconfig: Fix wrong __VA_ARGS__ usage Masami Hiramatsu
2020-02-08 11:10       ` Michael Ellerman
2020-02-09  4:09         ` Masami Hiramatsu
2020-02-09 13:05         ` [PATCH] tools/bootconfig: Suppress non-error messages Masami Hiramatsu
2020-02-10  2:06           ` Michael Ellerman
2020-02-10  7:18             ` Masami Hiramatsu
2020-02-10  9:50               ` Michael Ellerman
2020-02-10  9:50       ` [PATCH] tools/bootconfig: Fix wrong __VA_ARGS__ usage Michael Ellerman
2020-02-10 17:07         ` Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 07/26] tools: bootconfig: Add bootconfig test script Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 08/26] proc: bootconfig: Add /proc/bootconfig to show boot config list Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 09/26] init/main.c: Alloc initcall_command_line in do_initcall() and free it Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 10/26] bootconfig: init: Allow admin to use bootconfig for kernel command line Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 11/26] bootconfig: init: Allow admin to use bootconfig for init " Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 12/26] Documentation: bootconfig: Add a doc for extended boot config Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 13/26] tracing: Apply soft-disabled and filter to tracepoints printk Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 14/26] tracing: kprobes: Output kprobe event to printk buffer Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 15/26] tracing: kprobes: Register to dynevent earlier stage Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 16/26] tracing: Accept different type for synthetic event fields Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 17/26] tracing: Add NULL trace-array check in print_synth_event() Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 18/26] tracing/boot: Add boot-time tracing Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 19/26] tracing/boot: Add per-event settings Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 20/26] tracing/boot Add kprobe event support Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 21/26] tracing/boot: Add synthetic " Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 22/26] tracing/boot: Add instance node support Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 23/26] tracing/boot: Add cpu_mask option support Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 24/26] tracing/boot: Add function tracer filter options Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 25/26] Documentation: tracing: Add boot-time tracing document Steven Rostedt
2020-01-14 21:03 ` [for-next][PATCH 26/26] tracing: trigger: Replace unneeded RCU-list traversals Steven Rostedt
2020-01-14 22:11   ` Steven Rostedt

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