[dpdk-dev] [PATCH v9 3/9] linuxapp/eal_pci: get iommu class

[Thomas Monjalon]

06/10/2017 05:22, santosh:
> 
> On Friday 06 October 2017 05:47 AM, Thomas Monjalon wrote:
> > 20/09/2017 13:23, Santosh Shukla:
> >> +/** Device driver supports iova as va */
> >> +#define RTE_PCI_DRV_IOVA_AS_VA 0X0040
> > This flag name is surprizing and the comment does not help.
> > For the comment:
> > 	"Device driver supports I/O virtual addressing" ?
> > For the flag:
> > 	RTE_PCI_DRV_IOVA ?
> 
> Read [1].
> 
> V9 series went through evolution as a result of thorough review process.
> That name kept like above is - "Not for FUN", its for reason and its purpose
> to be explicit by saying that "driver need iova as va" mode. So as comment
> aligned on top says so.
> 
> Aron suggested to remove [1] and squash into this patch and that I did.
> 
> Your proposition is incorrect, Should says IOVA_AS_VA explicitly!.
> Request to follow work history, sorry I agains can't find you comment 
> logical.

Yes my proposal is not good.

> [1] http://dpdk.org/dev/patchwork/patch/27000/
> 
> > [...]
> >>  /*
> >> - * Get iommu class of pci devices on the bus.
> > This line has been added in previous patch.
> > Please fix it earlier.
> 
> What to fix? Be more explicit, can;t understand your comment.

You make this change:
- * Get iommu class of pci devices on the bus.
+ * Get iommu class of PCI devices on the bus.

It is better to write squash this uppercase change in
previous commit where you introduce this comment.

> > [...]
> >> +/*
> >> + * Any one of the device has iova as va
> >> + */
> >> +static inline int
> >> +pci_device_has_iova_va(void)
> > The name of this function does not suggest that it scans
> > every devices.
> 
> Its not scanning, It search for kdrv match. You misunderstood.
> disagree.

Yes my wording is not understandable.
By "scanning", I mean interating on lists.

About the function name, it could be:
	pci_one_device_has_iova_va
It better shows that the function check every devices.

> >> +{
> >> +	struct rte_pci_device *dev = NULL;
> >> +	struct rte_pci_driver *drv = NULL;
> >> +
> >> +	FOREACH_DRIVER_ON_PCIBUS(drv) {
> >> +		if (drv && drv->drv_flags & RTE_PCI_DRV_IOVA_AS_VA) {
> >> +			FOREACH_DEVICE_ON_PCIBUS(dev) {
> >> +				if (dev->kdrv == RTE_KDRV_VFIO &&
> >> +				    rte_pci_match(drv, dev))
> >> +					return 1;
> >> +			}
> > This is the reason of exporting the match function?
> > (note: match() is bus driver function, so it should not be exported)
> > Just because you get every devices without driver filtering?
> 
> I disagree, It is a bus function abstraction code w.r.t iommu class of device, 
> in case you missed reading source code and Implementation is correct.
> That needs exporting rte_pci_match(). Or else
> write code and show your code snippet as illustration, I doubt that you really
> understood this whole topic and its design theme.

OK, let's imagine I don't understand the whole topic.

> > There should be a better solution.
> > Please try to compare drv with dev->driver.

You could have answered that dev->driver is filled on probing
and you are doing the check before probing.

I don't want to continue this discussion.
We will rework which functions are exported when moving the PCI driver
out of EAL.