Re: xenstore utils dropped support for -s in 4.15

[Henrik Riomar <rio@riomar.se>]

On Sun, 11 Apr 2021 07:34:16 +0200
Juergen Gross <jgross@suse.com> wrote:

> On 11.04.21 00:02, Henrik Riomar wrote:
> > Hi,
> > 
> > In Alpine and Debian (probably elsewhere as well), the -s flag removed in these two commits:
> >   * https://github.com/xen-project/xen/commit/fa06cb8c38832aafe597d719040ba1d216e367b8
> >   * https://github.com/xen-project/xen/commit/c65687ed16d2289ec91036ec2862a4b4bd34ea4f
> > is actually used in the init scripts.

> > Reverting the two commits mentioned above restores a booting system.
> > 
> > The -s flag was introduced in 2005 or so, so I guess you can say that dropping it should
> > at least be mentioned in the release notices, and an alternative be described, or
> > -s functionally should be brought back.
> 
> The -s served exactly no purpose.

yes its used by dists to check that the socket is actually accessible (without falling back to 
direct access to /dev/xen/xenbus).

> 
> It was meant to force socket usage. A socket will be used anyway in
> case xenstored is running in dom0, so specifying -s won't change
> anything in this case. 

yes reverting the to commits above and using -s, brings back the original behavior, returning
with failure if the socket is not there.

There are two issues here I think:
 1. dists actually use -s to check if the daemon is up (and been doing this for a long time)
 2. Reads of /dev/xen/xenbus (via xenstore-read -s /), blocks for ever in 4.15

/ Henrik