Re: KDFONTOP/PIO_UNIMAPCLR: Input/output error

[Ludovic Courtès]

address@hidden (Ludovic Courtès) skribis:

> Danny Milosavljevic <address@hidden> skribis:
>
>>> PIO_UNIMAPCLR: Input/output error
>>> 3) PIO_UNIMAPCLR: Input/output error
>>> 
>>> Anything to worry about?
>>
>> According to 
>> https://elixir.bootlin.com/linux/v3.2/source/include/linux/kd.h#L70
>> that's trying to clear the Unicode -> font map (that is, charmap).
>>
>> In Linux, ./drivers/tty/vt/vt_ioctl.c implements it.
>>
>> Can't see how that ever ends up in -EIO O_o
>
> Sometimes we also get:
>
>   putfont: KDFONTOP: Input/output error
>
> In both cases, the warning comes from the ‘setfont’ program, invoked
> from ‘console-font-shepherd-services’.
>
> I’ve looked at the code and man pages and like you, I don’t see where
> EIO comes from.  Maybe it’s a generic ioctl error that’s return before
> we reach the actual ioctl implementation in the VT driver, sorta like
> EBADF?

I think I have a plausible explanation.  :-)  The EIO comes from
‘hung_up_tty_ioctl’ in drivers/tty/tty_io.c.  This is because mingetty
would call ‘vhangup’, and presumably, there was a time window where
‘setfont’ would find itself talking to a hung-up terminal.  QED.

Anyway, in commit a043b5b81a080c47e24298c80857919b9ea21bb2 I’ve added
--nohangup to mingetty and now ‘setfont’ is happy, and so am I.

Ludo’.