Re: [PATCH v1 5/5] console: support multiple serial console simultaneously

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Tue, Jun 10, 2025 at 02:48:54PM +0200, Jan Beulich wrote:
> On 25.05.2025 16:15, Marek Marczykowski-Górecki wrote:
> > Previously only one serial console was supported at the same time. Using
> > console=com1,dbgp,vga silently ignored all but last serial console (in
> > this case: only dbgp and vga were active).
> > 
> > Fix this by storing not a single sercon_handle, but an array of them, up
> > to MAX_SERCONS entries. The value of MAX_SERCONS can be chosen in
> > kconfig, the default (4) is arbitrary, inspired by the number of
> > SERHND_IDX values.
> > 
> > Make console_steal() aware of multiple consoles too. It can now either
> > steal output from specific console (for gdbstub), or from all of them at
> > once (for console suspend).
> > 
> > Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> > ---
> > This was posted before as part of initial xhci console submission, it
> > reached v6 (but last changes were in v4), but wasn't considered useful
> > enough to review/ack:
> > https://lore.kernel.org/xen-devel/Yu0XHUhsebE+WG0g@mail-itl/
> > 
> > Since I needed this feature again, to debug xhci console issue, I'm
> > including this patch again in the series.
> 
> Beyond this narrow aspect, has anything changed in the picture, compared
> to what was said / discussed earlier on?

Not really. It's still quite useful for people doing console drivers
debugging and have the luxury of having many options at the same time.
For me it's xhci, but it could be useful also for debugging other
drivers (outside of x86 too). And it's still not very useful for anybody
else.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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