lkml.org 
[lkml]   [2018]   [Jan]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v1 4/6] x86/boot: Assume MMIO if serial base address supplied via earlyprintk
From
Date
On Tue, 2018-01-16 at 04:13 +0100, Ingo Molnar wrote:
> * Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
>
> > If user supplied serial base address via kernel command line and
> > value
> > is higher than IO space limit (64k boundary), assume for now that
> > MMIO
> > byte access is required.
> >
> > Later we might expand or modify this if needed.
>
> Is this a standard pattern for serial code configuration values?

I didn't get what you meant under "standard" here.

IO space limit comes from generic io.h header and AFAIU is a hardware
limitation (outN (%dx), ...; inX (%dx); dx is 16 bit register).

Using mmio8 out of the IO space is dictated by the (modern) x86
platforms with non-standard (okay, high speed) UART location in address
space.

--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

\
 
 \ /
  Last update: 2018-01-16 11:57    [W:0.090 / U:3.788 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site