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Re: configuring /var/run with newer autoconf

It was <2016-04-11 pon 18:09>, when Florian Weimer wrote:
> On 04/11/2016 09:20 AM, Åukasz Stelmach wrote:
>> It was <2016-04-08 piÄ 14:31>, when Florian Weimer wrote:
>>> On 04/08/2016 09:52 AM, Åukasz Stelmach wrote:
>>>>> but you also have another option and what most people have been
>>>>> doing: c) symlink /var/run to /run
>>>> This does not help to avoid deadlocks at all.
>>> Why?  It may need changes to autofs, so that it can produce the
>>> required symbolic link, at an early stage of operation.
>> autofs works as expected, it does not provide any contents itself, instead it
>> intercepts all requests and put them on hold until the actual filesystem
>> is mounted. I wouldn't expect anything else.
> For generating the symlinks in /var, I would expect to provide them.
> Are you trying to automount /var itself, or is /var a directory
> monitored by the automounter?

I don't exactly understand the alternative. Let me try to describe what
happens in my system.

I've got a root fs. There is the /var directory. It is empty. There is

    LABEL=var    /var    ext4    defaults,noatime,x-systemd.automount    0 2

line in my fstab. x-systemd.automount tells systemd to mount autofs
under /var, start monitoring it for requests and mount the real ext4
file-system when a request comes.

>> I'd say the case we are discussing is an extremely rare corner case for
>> autofs and I'd rather expect requirement for autoconf 2.70 be accepted
>> in libc (-; before any kernel developer accepts a patch for autofs.
> It's not just autoconf (which, as far as I understand it, is not
> released at this point).   The pathname is part of the ABI, so we
> can't really change it for existing architectures.

I am not sure this is actually true. What is a part of ABI (as far as I
understand it) is _PATH_VARRUN defined in sysdeps/generic/paths.h and
sysdeps/unix/sysv/linux/paths.h. However, this isn't what nscd
uses. nscd has its own definitions in nscd/nscd-client.h and nscd/nscd.h
which apparently are not exported to /usr/include and are not supposed
to be used outside nscd. That means it should be possible to change the
the location wher nscd keeps its stuff without breaking ABI.

Åukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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