Re: [XEN][RFC PATCH v2 10/12] tools/libs/ctrl: Implement new xc interfaces for dt overlay

[Vikram Garhwal <fnu.vikram@xilinx.com>]

On Thu, Nov 11, 2021 at 04:54:25PM +0000, Anthony PERARD wrote:
Hi Anthony,
> On Mon, Nov 08, 2021 at 11:02:25PM -0800, Vikram Garhwal wrote:
> > xc_dt_overlay() sends the device tree binary overlay, size of .dtbo and overlay
> > operation type i.e. add or remove to xen.
> > 
> > Signed-off-by: Vikram Garhwal <fnu.vikram@xilinx.com>
> > ---
> >  tools/include/xenctrl.h      |  5 +++++
> >  tools/libs/ctrl/Makefile     |  1 +
> >  tools/libs/ctrl/xc_overlay.c | 51 ++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 57 insertions(+)
> >  create mode 100644 tools/libs/ctrl/xc_overlay.c
> > 
> > diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h
> > index 07b96e6..cfd7c5c 100644
> > --- a/tools/include/xenctrl.h
> > +++ b/tools/include/xenctrl.h
> > @@ -2684,6 +2684,11 @@ int xc_livepatch_replace(xc_interface *xch, char *name, uint32_t timeout, uint32
> >  int xc_domain_cacheflush(xc_interface *xch, uint32_t domid,
> >                           xen_pfn_t start_pfn, xen_pfn_t nr_pfns);
> >  
> > +#if defined (CONFIG_OVERLAY_DTB)
> > +int xc_dt_overlay(xc_interface *xch, void *overlay_fdt, int overlay_fdt_size,
> > +                  uint8_t overlayop);
> > +#endif
> > +
> >  /* Compat shims */
> >  #include "xenctrl_compat.h"
> >  
> > diff --git a/tools/libs/ctrl/Makefile b/tools/libs/ctrl/Makefile
> > index 519246b..a21a949 100644
> > --- a/tools/libs/ctrl/Makefile
> > +++ b/tools/libs/ctrl/Makefile
> > @@ -3,6 +3,7 @@ include $(XEN_ROOT)/tools/Rules.mk
> >  
> >  SRCS-y       += xc_altp2m.c
> >  SRCS-y       += xc_cpupool.c
> > +SRCS-$(CONFIG_OVERLAY_DTB) += xc_overlay.c
> 
> So, this patch seems to introduce the use of CONFIG_OVERLAY_DTB, is
> there a reason why the new functionality can't be always builtin?
> 
Above, if you meant removing "CONFIG_OEVRLAY_DTB" then here is my answer:
This feature is supported by ARM based FPGA devices only so there were a few
comments on v1 series to keep the code inside a config only. Now, for the tool
side also I kept the CONFIG_OVERLAY_DTB to align the xen-tools with Xen.

Although, now i saw your comments on patch 10 regarding  "always provide
libxl_dt_overlay() but which would return ENOSYS when libxl is built without
CONFIG_OVERLAY_DTB". That seems better approach here for all three xen-tool
patches.

Initially, i was not sure what to do here that's why i wrote a question in the
cover letter about this.

Also, do you know how to enable this config via menuconfig when building the Xen
tools? I know how to enable for Xen but not sure about tools.

Thanks for reviewing this.

Regards,
Vikram Garhwal

> Thanks,
> 
> -- 
> Anthony PERARD