| Message ID | 20200324150015.50496-2-roger.pau@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] xen: expand BALLOON_MEMORY_HOTPLUG description | expand |
On 24.03.20 16:00, Roger Pau Monne wrote: > Without it a PVH dom0 is mostly useless, as it would balloon down huge > amounts of RAM in order get physical address space to map foreign > memory and grants, ultimately leading to an out of memory situation. > > Such option is also needed for HVM or PVH driver domains, since they > also require mapping grants into physical memory regions. > > Suggested-by: Ian Jackson <ian.jackson@eu.citrix.com> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > --- > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > Cc: Juergen Gross <jgross@suse.com> > Cc: Stefano Stabellini <sstabellini@kernel.org> > Cc: xen-devel@lists.xenproject.org > --- > drivers/xen/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig > index 57ddd6f4b729..c344bcffd89d 100644 > --- a/drivers/xen/Kconfig > +++ b/drivers/xen/Kconfig > @@ -13,6 +13,7 @@ config XEN_BALLOON > config XEN_BALLOON_MEMORY_HOTPLUG > bool "Memory hotplug support for Xen balloon driver" > depends on XEN_BALLOON && MEMORY_HOTPLUG > + default y > help > Memory hotplug support for Xen balloon driver allows expanding memory > available for the system above limit declared at system startup. > Another variant would be to set: default XEN_BACKEND This would match the reasoning for switching it on. Either way would be fine with me, so you can add Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
On Tue, Mar 24, 2020 at 04:09:35PM +0100, Jürgen Groß wrote: > On 24.03.20 16:00, Roger Pau Monne wrote: > > Without it a PVH dom0 is mostly useless, as it would balloon down huge > > amounts of RAM in order get physical address space to map foreign > > memory and grants, ultimately leading to an out of memory situation. > > > > Such option is also needed for HVM or PVH driver domains, since they > > also require mapping grants into physical memory regions. > > > > Suggested-by: Ian Jackson <ian.jackson@eu.citrix.com> > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > > --- > > Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> > > Cc: Juergen Gross <jgross@suse.com> > > Cc: Stefano Stabellini <sstabellini@kernel.org> > > Cc: xen-devel@lists.xenproject.org > > --- > > drivers/xen/Kconfig | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig > > index 57ddd6f4b729..c344bcffd89d 100644 > > --- a/drivers/xen/Kconfig > > +++ b/drivers/xen/Kconfig > > @@ -13,6 +13,7 @@ config XEN_BALLOON > > config XEN_BALLOON_MEMORY_HOTPLUG > > bool "Memory hotplug support for Xen balloon driver" > > depends on XEN_BALLOON && MEMORY_HOTPLUG > > + default y > > help > > Memory hotplug support for Xen balloon driver allows expanding memory > > available for the system above limit declared at system startup. > > > > Another variant would be to set: default XEN_BACKEND > > This would match the reasoning for switching it on. I would rather have it always on if possible, as gntdev or privcmd (when used to map foreign pages from user-space) will also require it, and they are not gated on XEN_BACKEND AFAICT. > Either way would be fine with me, so you can add > > Reviewed-by: Juergen Gross <jgross@suse.com> Thanks! Roger.
Roger Pau Monne writes ("Re: [PATCH 2/2] xen: enable BALLOON_MEMORY_HOTPLUG by default"):
> I would rather have it always on if possible, as gntdev or privcmd
> (when used to map foreign pages from user-space) will also require it,
> and they are not gated on XEN_BACKEND AFAICT.
Currently there seem to be problems with this:
http://logs.test-lab.xenproject.org/osstest/logs/149014/test-amd64-amd64-dom0pvh-xl-intel/info.html
For now I have rolled back the change in osstest to enable this option
explicitly.
Ian.
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index 57ddd6f4b729..c344bcffd89d 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -13,6 +13,7 @@ config XEN_BALLOON config XEN_BALLOON_MEMORY_HOTPLUG bool "Memory hotplug support for Xen balloon driver" depends on XEN_BALLOON && MEMORY_HOTPLUG + default y help Memory hotplug support for Xen balloon driver allows expanding memory available for the system above limit declared at system startup.
Without it a PVH dom0 is mostly useless, as it would balloon down huge amounts of RAM in order get physical address space to map foreign memory and grants, ultimately leading to an out of memory situation. Such option is also needed for HVM or PVH driver domains, since they also require mapping grants into physical memory regions. Suggested-by: Ian Jackson <ian.jackson@eu.citrix.com> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> --- Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: xen-devel@lists.xenproject.org --- drivers/xen/Kconfig | 1 + 1 file changed, 1 insertion(+)