linux-kernel - Re: [PATCH] x86/setup: Deal with "quiet" commandline option earlier

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Message-ID: <d75ef785-d640-d396-43d3-95359096cd6a@redhat.com>
Date:   Tue, 4 Sep 2018 20:01:07 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Petr Mladek <pmladek@...e.com>,
        Maninder Singh <maninder1.s@...sung.com>
Subject: Re: [PATCH] x86/setup: Deal with "quiet" commandline option earlier

Hi,

On 04-09-18 17:25, Hans de Goede wrote:
> Hi,
> 
> On 04-09-18 16:42, Hans de Goede wrote:
>> X86's setup_arch() calls parse_early_param() somewhat late, to make
>> sure that everything is setup correcty to deal with earlyprintk over
>> the EHCI debug port.
>>
>> This means that a number of pr_info-s get done before
>> "early_param("quiet", quiet_kernel)" from init/main.c gets processed.
>>
>> Until commit 375899cddcbb ("printk: make sure to print log on console.")
>> this was not a problem because the printk code would evaluate the
>> console_loglevel vs the message-loglevel when flushing the buffer.
>>
>> After this commit the check is done at the time that pr_info is actually
>> called and the console_loglevel at calling time.
>>
>> This causes the following messages to get printed with the "quiet" option:
>>
>> [    0.000000] BIOS-provided physical RAM map:
>> [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x0000000000057fff] usable
>> ...
>> [    0.000000] BIOS-e820: [mem 0x0000000100000000-0x0000000874ffffff] usable
>>
>> This commit fixes this by making x86's setup_arch() explicitly check for
>> quiet early on.
>>
>> Cc: Petr Mladek <pmladek@...e.com>
>> Cc: Maninder Singh <maninder1.s@...sung.com>
>> Fixes: 375899cddcbb ("printk: make sure to print log on console.")
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> 
> Self-nack, I accidentally still had the revert of commit
> 375899cddcbb ("printk: make sure to print log on console.") in
> my tree while testing…
> 
> In order for my approach to work, we need to deal with the quiet
> option even earlier, before the first pr_notice in init/main.c,
> which requires access to the commandline before setup_arch()
> which is the function which fills the boot_command_line on
> several architectures.
> 
> So I think we need to look at a different approach.
> 
> I have one more idea, if that does not work out I think we
> just need to revert 375899cddcbb ("printk: make sure to print log on console.")

Ok, I have come up with a better, arch neutral fix, which no fully
lives in printk.c. I will keep the To/Cc of the new patch the same
to keep everyone in the loop.

Regards,

Hans


>> ---
>>   arch/x86/kernel/setup.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index b4866badb235..38f66b14cf3d 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -93,6 +93,7 @@
>>   #include <asm/processor.h>
>>   #include <asm/bugs.h>
>>   #include <asm/kasan.h>
>> +#include <asm/cmdline.h>
>>   #include <asm/vsyscall.h>
>>   #include <asm/cpu.h>
>> @@ -864,6 +865,16 @@ void __init setup_arch(char **cmdline_p)
>>       boot_cpu_data.x86_phys_bits = MAX_PHYSMEM_BITS;
>>   #endif
>> +#if !defined CONFIG_CMDLINE_BOOL || !defined CONFIG_CMDLINE_OVERRIDE
>> +    /*
>> +     * We call parse_early_param() somewhat late, see x86_configure_nx()
>> +     * comment. Deal with "quiet" here to suppress printing of early
>> +     * boot messages when quiet has been requested.
>> +     */
>> +    if (cmdline_find_option_bool(boot_command_line, "quiet"))
>> +        console_loglevel = CONSOLE_LOGLEVEL_QUIET;
>> +#endif
>> +
>>       /*
>>        * If we have OLPC OFW, we might end up relocating the fixmap due to
>>        * reserve_top(), so do this before touching the ioremap area.
>>