[syslinux] [PATCH 0/1] dprintf: add debug console support

Jonathan Boeing jonathan.n.boeing at gmail.com
Sun Feb 8 12:29:45 PST 2015

On Sun, 8 Feb 2015 11:37:34 -0800
Patrick Masotta <masottaus at yahoo.com> wrote:

> > This
> > doesn't support real hardware[1]; it's a VM-only
> > thing.
> Can't you just use a pipe?
> I debug on VMWare VMs with com2 redirected to a pipe that 
> then connects to a regular terminal; it's pretty fast.

I started out with serial redirection through QEMU, and it was
pretty slow (as in, count the lines scrolling past slow).  But I ran it
again to compare and the serial redirection was maybe just a little
slower than the debug console.  Not sure what I did wrong the first
time, but speed-wise the two methods are pretty close.

One other benefit of the debug console is that it makes it dead simple
to get interleaved output from multiple debug targets.  In my case,
I'm getting the messages from OVMF and syslinux.  It looks possible to
muck around with OVMF to get it to print over serial, but then you have
to worry about everyone playing nicely with the shared port.

So, redirected serial output would probably work, but the debug console
makes some use cases cleaner and simpler.

Jonathan Boeing

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