Re: [PATCH v3 3/3] tools: disable building qemu-trad per default

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Ian Jackson writes ("Re: [PATCH v3 3/3] tools: disable building qemu-trad per 
default"):
> Juergen Gross writes ("[PATCH v3 3/3] tools: disable building qemu-trad per 
> default"):
> > Using qemu-traditional as device model is deprecated for some time now.
> > 
> > So change the default for building it to "disable". This will affect
> > ioemu-stubdom, too, as there is a direct dependency between the two.
> > 
> > Today it is possible to use a PVH/HVM Linux-based stubdom as device
> > model. Additionally using ioemu-stubdom isn't really helping for
> > security, as it requires to run a very old and potentially buggy qemu
> > version in a PV domain. This is adding probably more security problems
> > than it is removing by using a stubdom.
> 
> Now that the relevant osstest patches are in and stable, I revisited
> this.  The downside risk to the release is very modest.  It might
> cause some temporary test breakage but is very easily reverted.
...
> And pushed to staging.

Unfortunately this broke the gitlab CI:

https://gitlab.com/xen-project/people/andyhhp/xen/-/jobs/1743723306

  === configuring in tools (/builds/xen-project/people/andyhhp/xen/tools)
  configure: running /bin/sh ./configure --disable-option-checking 
'--prefix=/usr/local'  '--enable-docs' 
'--with-system-seabios=/usr/share/seabios/bios.bin' 
'--with-system-ipxe=/usr/lib/ipxe/ipxe.pxe' '--disable-stubdom' 
'--with-extra-qemuu-configure-args="--disable-werror"' 
'--with-system-seabios=/bin/false' --cache-file=/dev/null --srcdir=.
  configure: WARNING: Setting CC, CFLAGS, LDFLAGS, LIBS, CPPFLAGS or CPP is not 
recommended, use PREPEND_INCLUDES, PREPEND_LIB, APPEND_INCLUDES and APPEND_LIB 
instead when possible.
  checking build system type... x86_64-pc-linux-musl
  ...
  checking for _FILE_OFFSET_BITS value needed for large files... no
  configure: error: Rombios is required to use IPXE
  configure: error: ./configure failed for tools

The configure arguments look coherent so this is surely a bug in the
configure script.

Looking at the code, it seems that there is code to enable rombios if
$enable_qemu_traditional, but nothing for ipxe.  This seems like a
bug, which was presumably masked by qemu-trad being enabled by
default.

With my RM hat on: Unfortunately I think this means this patch needs
to be reverted right away, at least for now, since it is causing a
regression.  I will do that now.

I would be open to reapplying it after the default for rombios is made
to depend on ipxe too, and ideally if we can see that the CI is happy
with the branch.

> The upside is that this will accelerate the total removal of qemu-trad
> by about one release cycle.  That is highly desirable.

So FTAOD although I am reverting this now, I am still in favour of it.

Thanks,
Ian.