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

From: Scott Wood
Date: Thu Sep 26 2013 - 18:20:58 EST


On Wed, 2013-09-25 at 22:53 -0500, Bhushan Bharat-R65777 wrote:
>
> > -----Original Message-----
> > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> > Sent: Wednesday, September 25, 2013 10:10 PM
> > To: Bhushan Bharat-R65777
> > Cc: joro@xxxxxxxxxx; benh@xxxxxxxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; linux-
> > pci@xxxxxxxxxxxxxxx; agraf@xxxxxxx; Wood Scott-B07421; iommu@xxxxxxxxxxxx
> > 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@xxxxxxxxxxxxx>
> > > ---
> > > 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



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