Re: [Xen-devel] how to disable build of pv-shim?

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, May 14, 2019 at 03:52:39AM -0600, Jan Beulich wrote:
> >>> On 14.05.19 at 11:23, <wei.liu2@xxxxxxxxxx> wrote:
> > On Tue, May 14, 2019 at 10:55:18AM +0200, Roger Pau Monné wrote:
> >> On Mon, May 13, 2019 at 04:28:12PM +0100, Wei Liu wrote:
> >> > On Mon, May 13, 2019 at 05:20:05PM +0200, Roger Pau Monné wrote:
> >> > > On Mon, May 13, 2019 at 04:53:21PM +0200, Olaf Hering wrote:
> >> > > > What is the recommended way to disable CONFIG_PV_SHIM, which is set 
> >> > > > in
> >> > > > tools/firmware/Makefile? From my understanding there is no way to 
> > influence
> >> > > > its value from outside, which means the build always enters xen-dir/.
> >> > > 
> >> > > I think the following should do the trick.
> >> > > 
> >> > > Let me know if that works for you and I will submit it formally.
> >> > > 
> >> > > Thanks!
> >> > > 
> >> > > ---8<---
> >> > > diff --git a/config/Tools.mk.in b/config/Tools.mk.in
> >> > > index 98245f63c9..84ddb1a542 100644
> >> > > --- a/config/Tools.mk.in
> >> > > +++ b/config/Tools.mk.in
> >> > > @@ -75,3 +75,5 @@ TINFO_LIBS          := @TINFO_LIBS@
> >> > >  ARGP_LDFLAGS        := @argp_ldflags@
> >> > >  
> >> > >  FILE_OFFSET_BITS    := @FILE_OFFSET_BITS@
> >> > > +
> >> > > +CONFIG_PV_SHIM      := @pvshim@
> >> > > diff --git a/tools/configure.ac b/tools/configure.ac
> >> > > index c9fd69ddfa..8df2fd604b 100644
> >> > > --- a/tools/configure.ac
> >> > > +++ b/tools/configure.ac
> >> > > @@ -492,4 +492,15 @@ AC_ARG_ENABLE([9pfs],
> >> > >  
> >> > >  AC_SUBST(ninepfs)
> >> > >  
> >> > > +AC_ARG_ENABLE([pvshim],
> >> > > +    AS_HELP_STRING([--disable-pvshim], [Disable pvshim build (x86 
> >> > > only, enabled by default)]),
> >> > > +    [AS_IF([test "x$enable_pvshim" = "xno"], [pvshim=n], 
> >> > > [pvshim=y])], [
> >> > > +    case "$host_cpu" in
> >> > > +        i[[3456]]86|x86_64)
> >> > > +           pvshim="y";;
> >> > 
> >> > Since xen doesn't build on 32bit anymore you may want to exclude
> >> > i[3456]86 here?
> >> 
> >> Oh, I didn't realize this. Is it true for all distros?
> > 
> > FAOD I was thinking about 32bit xen support. But I just realise since
> > you tested host_cpu here, maybe you intended to do a cross-build?
> 
> If the intention is a cross build, then host CPU shouldn't matter at
> all, i.e. building e.g. on Arm should work as well.
> 
> When considering the target CPU, implying a 64-bit hypervisor from
> a 32-bit general (i.e. tool stack) target would of course be an option.
> Question just is how you would determine whether a suitable cross
> tool chain is available.

I think it would better to use target_cpu here, but limiting to x86_64
only seems wrong, since a user could build a 32bit toolstack and have
a 64bit pvshim. I'm not sure however if there are other issues that
would prevent this from working out of the box.

Thanks, Roger.

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