| Message ID | 20200720112137.27327-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] docs: specify stability of hypfs path documentation | expand |
> -----Original Message----- > From: Juergen Gross <jgross@suse.com> > Sent: 20 July 2020 12:22 > To: xen-devel@lists.xenproject.org > Cc: paul@xen.org; Juergen Gross <jgross@suse.com>; Andrew Cooper <andrew.cooper3@citrix.com>; George > Dunlap <george.dunlap@citrix.com>; Ian Jackson <ian.jackson@eu.citrix.com>; Jan Beulich > <jbeulich@suse.com>; Julien Grall <julien@xen.org>; Stefano Stabellini <sstabellini@kernel.org>; Wei > Liu <wl@xen.org> > Subject: [PATCH v3] docs: specify stability of hypfs path documentation > > In docs/misc/hypfs-paths.pandoc the supported paths in the hypervisor > file system are specified. Make it more clear that path availability > might change, e.g. due to scope widening or narrowing (e.g. being > limited to a specific architecture). > > Signed-off-by: Juergen Gross <jgross@suse.com> > Release-acked-by: Paul Durrant <paul@xen.org> TBC, this is also exempt from the commit moratorium as it really needs to be in 4.14. Paul > --- > V2: reworded as requested by Jan Beulich > V3: reworded again as suggested by George Dunlap > --- > docs/misc/hypfs-paths.pandoc | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/docs/misc/hypfs-paths.pandoc b/docs/misc/hypfs-paths.pandoc > index a111c6f25c..68d83d9245 100644 > --- a/docs/misc/hypfs-paths.pandoc > +++ b/docs/misc/hypfs-paths.pandoc > @@ -5,6 +5,9 @@ in the Xen hypervisor file system (hypfs). > > The hypervisor file system can be accessed via the xenhypfs tool. > > +The availability of the hypervisor file system depends on the hypervisor > +config option CONFIG_HYPFS, which is on per default. > + > ## Notation > > The hypervisor file system is similar to the Linux kernel's sysfs. > @@ -64,6 +67,23 @@ the list elements separated by spaces, e.g. "dom0 PCID-on". > The entry would be writable and it would exist on X86 only and only if the > hypervisor is configured to support PV guests. > > +# Stability > + > +Path *presence* is not stable, but path *meaning* is always stable: if a tool > +you write finds a path present, it can rely on behavior in future versions of > +the hypervisors, and in different configurations. Specifically: > + > +1. Conditions under which paths are used may be extended, restricted, or > + removed. For example, a path that’s always available only on ARM systems > + may become available on x86; or a path available on both systems may be > + restricted to only appearing on ARM systems. Paths may also disappear > + entirely. > +2. However, the meaning of a path will never change. If a path is present, > + it will always have exactly the meaning that it always had. In order to > + maintain this, removed paths should be retained with the tag [REMOVED]. > + The path may be restored *only* if the restored version of the path is > + compatible with the previous functionality. > + > ## Example > > A populated Xen hypervisor file system might look like the following example: > -- > 2.26.2
On 20.07.2020 13:21, Juergen Gross wrote: > In docs/misc/hypfs-paths.pandoc the supported paths in the hypervisor > file system are specified. Make it more clear that path availability > might change, e.g. due to scope widening or narrowing (e.g. being > limited to a specific architecture). > > Signed-off-by: Juergen Gross <jgross@suse.com> > Release-acked-by: Paul Durrant <paul@xen.org> Acked-by: Jan Beulich <jbeulich@suse.com> Paul - should I throw this in right away, or has it now rather missed the train? Jan
> -----Original Message----- > From: Jan Beulich <jbeulich@suse.com> > Sent: 20 July 2020 12:33 > To: Juergen Gross <jgross@suse.com>; paul@xen.org > Cc: xen-devel@lists.xenproject.org; Andrew Cooper <andrew.cooper3@citrix.com>; George Dunlap > <george.dunlap@citrix.com>; Ian Jackson <ian.jackson@eu.citrix.com>; Julien Grall <julien@xen.org>; > Stefano Stabellini <sstabellini@kernel.org>; Wei Liu <wl@xen.org> > Subject: Re: [PATCH v3] docs: specify stability of hypfs path documentation > > On 20.07.2020 13:21, Juergen Gross wrote: > > In docs/misc/hypfs-paths.pandoc the supported paths in the hypervisor > > file system are specified. Make it more clear that path availability > > might change, e.g. due to scope widening or narrowing (e.g. being > > limited to a specific architecture). > > > > Signed-off-by: Juergen Gross <jgross@suse.com> > > Release-acked-by: Paul Durrant <paul@xen.org> > > Acked-by: Jan Beulich <jbeulich@suse.com> > > Paul - should I throw this in right away, or has it now rather missed > the train? I guess our emails raced. Throw it in now. Paul > > Jan
On 20.07.2020 13:34, Paul Durrant wrote: >> -----Original Message----- >> From: Jan Beulich <jbeulich@suse.com> >> Sent: 20 July 2020 12:33 >> To: Juergen Gross <jgross@suse.com>; paul@xen.org >> Cc: xen-devel@lists.xenproject.org; Andrew Cooper <andrew.cooper3@citrix.com>; George Dunlap >> <george.dunlap@citrix.com>; Ian Jackson <ian.jackson@eu.citrix.com>; Julien Grall <julien@xen.org>; >> Stefano Stabellini <sstabellini@kernel.org>; Wei Liu <wl@xen.org> >> Subject: Re: [PATCH v3] docs: specify stability of hypfs path documentation >> >> On 20.07.2020 13:21, Juergen Gross wrote: >>> In docs/misc/hypfs-paths.pandoc the supported paths in the hypervisor >>> file system are specified. Make it more clear that path availability >>> might change, e.g. due to scope widening or narrowing (e.g. being >>> limited to a specific architecture). >>> >>> Signed-off-by: Juergen Gross <jgross@suse.com> >>> Release-acked-by: Paul Durrant <paul@xen.org> >> >> Acked-by: Jan Beulich <jbeulich@suse.com> >> >> Paul - should I throw this in right away, or has it now rather missed >> the train? > > I guess our emails raced. Throw it in now. Indeed they did - I saw yours come in right after sending. Change is in now. Jan
diff --git a/docs/misc/hypfs-paths.pandoc b/docs/misc/hypfs-paths.pandoc index a111c6f25c..68d83d9245 100644 --- a/docs/misc/hypfs-paths.pandoc +++ b/docs/misc/hypfs-paths.pandoc @@ -5,6 +5,9 @@ in the Xen hypervisor file system (hypfs). The hypervisor file system can be accessed via the xenhypfs tool. +The availability of the hypervisor file system depends on the hypervisor +config option CONFIG_HYPFS, which is on per default. + ## Notation The hypervisor file system is similar to the Linux kernel's sysfs. @@ -64,6 +67,23 @@ the list elements separated by spaces, e.g. "dom0 PCID-on". The entry would be writable and it would exist on X86 only and only if the hypervisor is configured to support PV guests. +# Stability + +Path *presence* is not stable, but path *meaning* is always stable: if a tool +you write finds a path present, it can rely on behavior in future versions of +the hypervisors, and in different configurations. Specifically: + +1. Conditions under which paths are used may be extended, restricted, or + removed. For example, a path that’s always available only on ARM systems + may become available on x86; or a path available on both systems may be + restricted to only appearing on ARM systems. Paths may also disappear + entirely. +2. However, the meaning of a path will never change. If a path is present, + it will always have exactly the meaning that it always had. In order to + maintain this, removed paths should be retained with the tag [REMOVED]. + The path may be restored *only* if the restored version of the path is + compatible with the previous functionality. + ## Example A populated Xen hypervisor file system might look like the following example:
In docs/misc/hypfs-paths.pandoc the supported paths in the hypervisor file system are specified. Make it more clear that path availability might change, e.g. due to scope widening or narrowing (e.g. being limited to a specific architecture). Signed-off-by: Juergen Gross <jgross@suse.com> Release-acked-by: Paul Durrant <paul@xen.org> --- V2: reworded as requested by Jan Beulich V3: reworded again as suggested by George Dunlap --- docs/misc/hypfs-paths.pandoc | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)