Hi Richard,

your dts has the 'l4vmm,vcon_cap = "uart";' enabled (not commented out),
thus the 8250 UART emulation in uvmm looks for a "uart" capability which
is not there and thus disables the virtual UART. Removing that line or
commenting it out will make this work I believe as the standard
capability will be used then.


Adam

On Mon Apr 14, 2025 at 11:57:32 +0000, Richard Clark wrote:
> Adam,
> 
> Yes the vm-basic.cfg is where I started.
> 
> I am attaching a tgz file with two directories showing the two different 
> outputs that I get when
> trying to run hvc0 and ttyS0. Included are the config files, the ramdisk, and 
> the dts as well.
> 
> 
> Richard
> 
> 
> -----Original Message-----
> From: Adam Lackorzynski <[email protected]> 
> Sent: Monday, April 14, 2025 12:49 AM
> To: Richard Clark <[email protected]>; 
> [email protected]
> Cc: Bud Wykoff <[email protected]>
> Subject: Re: Linux console?
> 
> Hi Richard,
> 
> On Fri Apr 11, 2025 at 15:27:18 +0000, Richard Clark wrote:
> > L4Re,
> > 
> > I’ve been working with the examples and tweaking them for AMD64 
> > (QEMU), and I’ve managed to get linux up and booting, reading the 
> > ramdisk, and even spawning a login process which kicks off /bin/sh and 
> > displays a # prompt. And that’s great, but that’s all it does. I can’t 
> > get any input to it. That’s using the device hvc0. Of course uvmm 
> > complains that there is no virtual console and warns that it might not 
> > work, so the software is at least not surprised! 😊 But when I try to 
> > use the device ttyS0, linux stops printing even before the login 
> > process tries to run. I don’t get any errors, but also no output. And 
> > I can’t seem to run the IO server because then linux won’t load at all 
> > (something about out-of-memory).
> > 
> > I’m sure I’m missing some little piece of magic somewhere, but I can’t 
> > find any working examples. None of them have active logins (I had to 
> > add my own iniittab to the ramdisk). A little help connecting the cons 
> > service to my linux so I can get a real bash shell? Or running IO and 
> > connecting through that?
> 
> Did you try to run for example the "VM-basic" entry that is there? That is 
> supposed to be a minimal working example.
> Please also provide the output from the system you're getting, that is 
> helping understanding what's going on.
> 
> 
> Thanks, Adam

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