Re: [PATCH] remaining steps for time64 switchover

[Matias Fonzo <selk@dragora.org>]

Hello Laurent,

Can utmps work without s6?.  I mean, independently of the init system or 
distribution...

El 2019-10-27 05:32, Laurent Bercot escribió:
>> Or here. So, the story on utmpx: we can either
>> 
>> 1. match the current size on 32-bit archs, but move the timeval to
>>    unused space at the end where a time64 version fits, or
>> 
>> 2. match the current size and layout of the 64-bit struct, making it
>>    possible to share records between 32- and 64-bit processes on the
>>    same machine.
>> 
>> Keep in mind that this struct is not used anywhere in libc presently,
>> but normally it's used as a format for on-disk records.
>> 
>> I'm kinda leaning towards option 2, but being that I don't use (and
>> hate) utmp, I'd rather hear opinions from people who do use it. Either
>> way time fields in existing data will break, so it's a question of
>> whether that one-time breakage is already sufficient to go a bit
>> further and get 32/64 compat afterwards.
> 
> I don't use the libc's utmpx, but I maintain utmps, which is a secure
> implementation of utmp, including the definition of struct utmpx.
> I haven't been following the time64 thing closely. The current struct
> utmpx definition includes a struct timeval. Will it need to change,
> or will musl's struct timeval change be enough and naturally propagate
> so the struct utmpx will become time64-compatible?
> 
> On-disk data is not a problem. On the distro that I know uses utmps
> (Adélie), the utmp/wtmp records, by design, do not survive a reboot,
> so a reboot will fix everything - and will be mandatory anyway on
> arches where the musl ABI changes.
> 
> I'm not aware of any distribution that uses musl, doesn't use utmps,
> and still keeps on-disk utmpx records.
> 
> --
> Laurent