[dpdk-dev] [PATCH v2] igb_uio: fix possible mmap failure for Linux > v4.3

De Lara Guarch, Pablo pablo.de.lara.guarch at intel.com
Fri Jul 1 17:52:31 CEST 2016


Hi Ferruh,

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ferruh Yigit
> Sent: Friday, July 01, 2016 4:08 PM
> To: dev at dpdk.org
> Cc: Stephen Hemminger
> Subject: [dpdk-dev] [PATCH v2] igb_uio: fix possible mmap failure for Linux >
> v4.3
> 
> mmap the iomem range of the PCI device fails for kernels that
> enabled CONFIG_IO_STRICT_DEVMEM option:
> 
> EAL: pci_map_resource():
>          cannot mmap(39, 0x7f1c51800000, 0x100000, 0x0):
>          Invalid argument (0xffffffffffffffff)
> 
> CONFIG_IO_STRICT_DEVMEM is introduced in Linux v4.4 and not enabled
> by default:

This was introduced in kernel 4.5 (change the title as well ;))

> Linux commit: 90a545e restrict /dev/mem to idle io memory ranges
> 
> As a workaround igb_uio can stop reserving PCI memory resources, from
> kernel point of view iomem region looks like idle and mmap works
> again. This matches uio_pci_generic usage.
> 
> With this update device iomem range is not protected against any
> other kernel drivers or userspace access. But this  shouldn't
> be a problem for dpdk usage module since purpose of the igb_uio
> module is to provide userspace access.
> 
> Fixes: af75078fece3 ("first public release")
> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>



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