Messages in this thread | | | Subject | Re: [PATCH] x86/x86_64_defconfig: Enable the serial console | From | Guillaume Tucker <> | Date | Mon, 12 Oct 2020 16:10:45 +0100 |
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On 12/10/2020 15:40, Willy Tarreau wrote: > On Mon, Oct 12, 2020 at 04:32:12PM +0200, Borislav Petkov wrote: >> On Mon, Oct 12, 2020 at 11:22:10AM +0100, Guillaume Tucker wrote: >>> However, it was found while adding some x86 Chromebooks[1] to >>> KernelCI that x86_64_defconfig lacked some basic things for >>> anyone to be able to boot a kernel with a serial console enabled >>> on those. >> >> Hold on, those are laptops, right? How come they do have serial console? >> Because laptops don't have serial console - that has been the eternal >> problem with debugging kernels on laptops.
Yes the link you pointed at is a prerequisite to enable serial console in the firmware (Coreboot/Depthcharge).
> Well, to be precise, they don't have *anymore*. I used to exclusively > select laptops having a serial port given that I was using it daily with > routers, until I had to resign when I abandonned my good old NC8000 :-/
You can get serial console on recent enough Chromebooks with a debug interface such as SuzyQable:
https://www.sparkfun.com/products/14746
It's not a USB Type-C adapter, it has a debug interface which works with Chromebooks that support Case-Closed Debugging. Anyone can do that without modifying the Chromebook, and with a bit of patience to go through the documentation[1]...
The KernelCI sample results from my previous email were run using just that: off-the-shelf Chromebooks + SuzyQ + rebuilt firmware for interactive console and tftp boot + kernel with the config options in Enric's patch.
Thanks, Guillaume
[1] https://chromium.googlesource.com/chromiumos/platform/ec/+/cr50_stab/docs/case_closed_debugging_cr50.md
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