linux-kernel - Re: [PATCH v5 2/2] arch/x86: remove pci uart early console from early

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Message-ID: <20150603163447.GA149091@worksta>
Date:	Wed, 3 Jun 2015 09:34:47 -0700
From:	Bin Gao <bin.gao@...ux.intel.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Stuart R. Anderson" <stuart.r.anderson@...el.com>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Jiri Slaby <jslaby@...e.cz>, Borislav Petkov <bp@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] arch/x86: remove pci uart early console from
 early_prink.c

On Wed, Jun 03, 2015 at 08:35:29AM -0400, Peter Hurley wrote:
> > +/* x86 uses "earlyprintk=xxx", so we keep the compatibility here */
> > +#ifdef CONFIG_X86
> > +static int __init param_setup_earlycon_x86(char *buf)
> > +{
> > +	return param_setup_earlycon(buf);
> > +}
> > +early_param("earlyprintk", param_setup_earlycon_x86);
> 
> I'm concerned that this effectively makes earlyprintk= a synonym for
> earlycon=, which may have unforeseen consequences. I'd rather this
> specifically parse for replacement functionality, ie., only command line
> parameters of the form:
> 
> 	earlyprintk=pciserial,...
> 
> Regards,
> Peter Hurley
> 

Something like this: ?

/*
 * x86 uses "earlyprintk=xxx", so we keep the compatibility here.
 * But we only handle the earlyprintk=uart8250,pci[32]B:D.F[,options] case.
 */
#ifdef CONFIG_X86
static int __init param_setup_earlycon_x86(char *buf)
{
        if (strncmp("uart8250,pci", 12))
                return -EINVAL;
 
        return param_setup_earlycon(buf);
}
early_param("earlyprintk", param_setup_earlycon_x86);

Thanks,
Bin

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