Re: [PATCH v3 2/2] xen/console: unify printout behavior for UART emulators

[dmkhn@xxxxxxxxx]

On Sat, Jun 28, 2025 at 06:26:12PM +0100, Julien Grall wrote:
> Hi Stefano,
> 
> On 21/06/2025 01:52, Stefano Stabellini wrote:
> >> Widely used or not - _I_ use it all the time in debug configs where serial
> >> is available.
> >
> > Fair enough and your usage is really important for the project. At the
> > same time you know exactly what's going on so you wouldn't be confused
> > by the presence or absence of a (d0) prefix.
> >
> > The main issue is when less familiar users try Xen, or less familiar
> > developers go through the Xen source code to learn from it.
> >
> > I would optimize this choice to make it simpler for users and to make
> > the code simpler. Your use-case is really important as well, but I would
> > trust you to understand what's going on either way, with or without the
> > (d0) prefix.
> 
> Thanks for the clarification. I gave a try with and without the series
> to understand a bit more the difference. I think there are some
> imbalance in that setup because when the focus is on Xen, the logs are
> still prefixed with "(XEN)". So naturally the log with no prefix are the
> one for Dom0. So I have to agree with Jan here.
> 
> I haven't tried the behavior with dom0less. So I am not sure what would
> happen if the focus switch to Xen.
> 
> Also, when switching focus, I have noticed a very odd behavior with this
> patch. "(d0)" is printed multiple time per line:

Thanks for catching this, will fix.

> 
> "
> (d0) [    1.344020] v(d0) gaarb: loaded
> (d0) [    1.352808] c(d0) locksource: Swit(d0) ched to clocksou(d0) rce
> arch_sys_cou(d0) nter
> (d0) [    1.367604] V(d0) FS: Disk quotas (d0) dquot_6.6.0
> (d0) [    1.369369] V(d0) FS: Dquot-cache (d0) hash table entri(d0) es:
> 512 (order 0(d0) , 4096 bytes)
> (d0) [    1.376766] p(d0) np: PnP ACPI: di(d0) sabled
> (d0) [    1.619730] N(d0) ET: Registered P(d0) F_INET protocol (d0) family
> (d0) [    1.623635] I(d0) P idents hash ta(d0) ble entries: 163(d0) 84
> (order: 5, 13(d0) 1072 bytes, line(d0) ar)
> (d0) [    1.636915] t(d0) cp_listen_portad(d0) dr_hash hash tab(d0) le
> entries: 512 (d0) (order: 3, 36864(d0)  bytes, linear)
> (d0) [    1.638331] T(d0) able-perturb has(d0) h table entries:(d0)
> 65536 (order: 6(d0) , 262144 bytes, (d0) linear)
> (d0) [    1.639267] T(d0) CP established h(d0) ash table entrie(d0) s:
> 8192 (order: (d0) 4, 65536 bytes, (d0) linear)
> (d0) [    1.643457] T(d0) CP bind hash tab(d0) le entries: 8192(d0)
> (order: 8, 1179(d0) 648 bytes, linea(d0) r)
> (d0) [    1.652078] T(d0) CP: Hash tables (d0) configured (esta(d0)
> blished 8192 bin(d0) d 8192)
> (d0) [    1.655824] U(d0) DP hash table en(d0) tries: 512 (orde(d0) r:
> 4, 81920 byte(d0) s, linear)
> (d0) [    1.657807] U(d0) DP-Lite hash tab(d0) le entries: 512 (d0)
> (order: 4, 81920(d0)  bytes, linear)
> (d0) [    1.661993] N(d0) ET: Registered P(d0) F_UNIX/PF_LOCAL (d0)
> protocol family
> (d0) [    1.674980] R(d0) PC: Registered n(d0) amed UNIX socket(d0)
> transport modul(d0) e.
> (d0) [    1.676034] R(d0) PC: Registered u(d0) dp transport mod(d0) ule.
> (d0) [    1.677241] R(d0) PC: Registered t(d0) cp transport mod(d0) ule.
> (d0) [    1.677964] R(d0) PC: Registered t(d0) cp-with-tls tran(d0)
> sport module.
> (d0) [    1.678615] R(d0) PC: Registered t(d0) cp NFSv4.1 backc(d0)
> hannel transport(d0)  module.
> "
> 
> Cheers,
> 
> --
> Julien Grall
> 
>