[Ksummit-discuss] [TECH TOPIC] asynchronous printk

David Woodhouse dwmw2 at infradead.org
Thu Jul 21 14:40:32 UTC 2016


On Thu, 2016-07-21 at 07:21 -0700, Josh Triplett wrote:
> On Thu, Jul 21, 2016 at 12:59:18PM +0100, David Woodhouse wrote:
> > On Thu, 2016-07-21 at 04:19 -0700, Josh Triplett wrote:
> > > I've run into various cases where "console=ttyS0,115200" didn't produce
> > > any serial output at all, but "earlyprintk=ttyS0,115200,keep" did.
> > 
> > Note that those are very different things. Because 'ttyS0' for
> > earlyprintk really means '16x50 UART at 0x3f8'. While the later one
> > actually depends on it being discovered by the various options we have
> > for finding them, some of which are only available quite late.
> 
> Given the discussion in this thread about wanting to eliminate
> earlyprintk in favor of a unified mechanism that works as early as
> possible, how would this case work on the system I described above where
> earlyprintk works and console doesn't?

We'd need to look at why, and fix the driver so that it *does* work.

But that should be a driver-specific issue.

-- 
dwmw2
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