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

On Wed, 2013-09-25 at 22:53 -0500, Bhushan Bharat-R65777 wrote:

quoted

-----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:

quoted

Signed-off-by: Bharat Bhushan <redacted>
---
 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,

quoted

 			       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