linux-kernel - Re: [PATCH v2 7/7] x86/boot: Support nocfg parameter for earlyprintk

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 28 Mar 2019 16:27:56 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/7] x86/boot: Support nocfg parameter for earlyprintk

On Thu, Mar 28, 2019 at 03:13:07PM +0100, Borislav Petkov wrote:
> On Thu, Mar 28, 2019 at 04:00:39PM +0200, Andy Shevchenko wrote:
> > If it's _non-standard_ serial interface (by meaning of I/O accessors and port
> > addresses), user may consider to use this options in case the interface to
> > communicate with kernel is serial one and its configuration is done by other
> > means (firmware / bootloader / EFI / etc).
> 
> And is this non-standard interface out there in the wild or only at
> Intel's labs?

Of course in the wild.

> Are there boxes like that out there?

One at hand now is called Intel Edison.

> If I go to the store and buy a box, how do I know whether that box would
> need "nocfg"? Do I look in the BIOS or how do I find out I need to supply
> "nocfg"?

By reading some technical documentation I suppose.
What is your point here? earlyprintk is a mechanism for _debugging_, I suppose
the user should have slightly more knowledge than user.

> > If by BIOS or by other means the serial port is configured
> 
> How do I find out that the serial port is configured?

If you _already_ connected via it and get firmware / bootloader messages.

-- 
With Best Regards,
Andy Shevchenko