Re: [PATCH 5/7] iommu: supress loff_t compilation error on powerpc

[Scott Wood <scottwood@freescale.com>]

On Wed, 2013-09-25 at 22:53 -0500, Bhushan Bharat-R65777 wrote:
> 
> > -----Original Message-----
> > From: Alex Williamson [mailto:alex.williamson@redhat.com]
> > Sent: Wednesday, September 25, 2013 10:10 PM
> > To: Bhushan Bharat-R65777
> > Cc: joro@8bytes.org; benh@kernel.crashing.org; galak@kernel.crashing.org; linux-
> > kernel@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux-
> > pci@vger.kernel.org; agraf@suse.de; Wood Scott-B07421; iommu@lists.linux-
> > foundation.org; Bhushan Bharat-R65777
> > Subject: Re: [PATCH 5/7] iommu: supress loff_t compilation error on powerpc
> > 
> > On Thu, 2013-09-19 at 12:59 +0530, Bharat Bhushan wrote:
> > > Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
> > > ---
> > >  drivers/vfio/pci/vfio_pci_rdwr.c |    3 ++-
> > >  1 files changed, 2 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c
> > > b/drivers/vfio/pci/vfio_pci_rdwr.c
> > > index 210db24..8a8156a 100644
> > > --- a/drivers/vfio/pci/vfio_pci_rdwr.c
> > > +++ b/drivers/vfio/pci/vfio_pci_rdwr.c
> > > @@ -181,7 +181,8 @@ ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char
> > __user *buf,
> > >  			       size_t count, loff_t *ppos, bool iswrite)  {
> > >  	int ret;
> > > -	loff_t off, pos = *ppos & VFIO_PCI_OFFSET_MASK;
> > > +	loff_t off;
> > > +	u64 pos = (u64 )(*ppos & VFIO_PCI_OFFSET_MASK);
> > >  	void __iomem *iomem = NULL;
> > >  	unsigned int rsrc;
> > >  	bool is_ioport;
> > 
> > What's the compile error that this fixes?
> 
> I was getting below error; and after some googling I came to know that this is how it is fixed by other guys.
> 
> /home/r65777/linux-vfio/drivers/vfio/pci/vfio_pci_rdwr.c:193: undefined reference to `__cmpdi2'
> /home/r65777/linux-vfio/drivers/vfio/pci/vfio_pci_rdwr.c:193: undefined reference to `__cmpdi2'

It looks like PPC Linux implements __ucmpdi2, but not the signed
version.  That should be fixed, rather than hacking up random code to
avoid it.

-Scott