[dpdk-dev] [PATCH] eal: map io resources for non x86 architectures

[Yuanhan Liu]

On Wed, Dec 16, 2015 at 07:21:55PM +0530, Santosh Shukla wrote:
> On Wed, Dec 16, 2015 at 6:18 PM, Yuanhan Liu
> <yuanhan.liu at linux.intel.com> wrote:
> > On Wed, Dec 16, 2015 at 01:31:04PM +0100, David Marchand wrote:
> >> x86 requires a special set of instructions to access ioports, but other
> >> architectures let you remap io resources.
> >> So let eal remap io resources by accepting IORESOURCE_IO flag for
> >> architectures other than x86.
> >
> > One question: this patch could be a replacement of the igbuio_iomap patch
> > from Santosh? If so, I like it: It's more elegant.
> >
> >         --yliu
> >
> 
> I did tried similar in past but not in parse_sysfs (such that
> mem.resource_addr to accept IO_RESOURCE_IO types) and observed that
> pci_map_resource not able to map address hence segfault at tespmd
> initialization.
> 
> i was getting these:
> EAL: pci_map_resource(): cannot mmap(19, 0x7fa5c00000, 0x20, 0x0):
> Invalid argument (0xffffffffffffffff)

That's because ARM (at least the kernel) doesn't allow an IO map:

arch/arm/kernel/bios32.c
------------------------
618 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
619                         enum pci_mmap_state mmap_state, int write_combine)
620 {
621         if (mmap_state == pci_mmap_io)
622                 return -EINVAL;

And with a quick glimpse of powerpc, I see no such limitation. Hence,
this peice of code may work only on Powerpc platform (and maybe a few
others we don't care).

So, apparently, this will not work for ARM.

	--yliu