Re: [PATCH v4 2/8] emul/vuart: introduce framework for UART emulators

[dmkhn@proton.me]

On Tue, Aug 12, 2025 at 08:52:18AM +0200, Jan Beulich wrote:
> On 12.08.2025 01:55, dmkhn@proton.me wrote:
> > On Mon, Aug 11, 2025 at 09:34:58AM +0200, Jan Beulich wrote:
> >> On 09.08.2025 20:55, dmkhn@proton.me wrote:
> >>> On Mon, Aug 04, 2025 at 12:11:03PM +0200, Jan Beulich wrote:
> >>>> On 31.07.2025 21:21, dmkhn@proton.me wrote:
> >>>>> @@ -354,6 +355,8 @@ static void cf_check dump_domains(unsigned char key)
> >>>>>                             v->periodic_period / 1000000);
> >>>>>              }
> >>>>>          }
> >>>>> +
> >>>>> +        vuart_dump_state(d);
> >>>>
> >>>> How verbose is this going to get?
> >>>
> >>> Looks something like this:
> >>> ```
> >>> (XEN) [   88.334893] 'q' pressed -> dumping domain info (now = 88334828303)
> >>> [..]
> >>> (XEN) [   88.335673] Virtual ns16550 (COM2) I/O port 0x02f8 IRQ#3 owner d0
> >>> (XEN) [   88.335681]   RX FIFO size 1024 in_prod 258 in_cons 258 used 0
> >>> (XEN) [   88.335689]   TX FIFO size 2048 out_prod 15 out_cons 0 used 15
> >>> (XEN) [   88.335696]   00 RBR 02 THR 6f DLL 01 DLM 00
> >>> (XEN) [   88.335703]   01 IER 05
> >>> (XEN) [   88.335709]   02 FCR 81 IIR c1
> >>> (XEN) [   88.335715]   03 LCR 13
> >>> (XEN) [   88.335720]   04 MCR 0b
> >>> (XEN) [   88.335726]   05 LSR 60
> >>> (XEN) [   88.335731]   06 MSR b0
> >>> (XEN) [   88.335736]   07 SCR 00
> >>>
> >>> ```
> >>
> >> Definitely too much (for my taste) to put under 'q'.
> >
> > I'll try to limit the number of printed lines; register dump can be made
> > compact for sure.
> 
> Yet even then I'm inclined to say that device specific data simply doesn't
> belong here.

Ability to produce such traces was helpful during debug, TBH.

I will hide per-vuart dump_state behind CONFIG_VUART_DUMP_STATE (or alike)
so default config does not enable it.