> -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Ferruh Yigit > Sent: Friday, July 01, 2016 11:53 AM > To: Mcnamara, John; dev at dpdk.org > Cc: De Lara Guarch, Pablo; Stephen Hemminger > Subject: Re: [dpdk-dev] Issue with igb_uio in Fedora 24 > > On 7/1/2016 11:21 AM, Mcnamara, John wrote: > > Hi, > > > > We have seen an issue when using the igb_uio module in Fedora > > 24. However, it relates to kernel 4.5+ so it could occur in other > > distros/oses. > > > > The issue occurs after binding a nic to igb_uio: > > > > # ./tools/dpdk_nic_bind.py -b igb_uio 0000:03:00.0 > > # ./x86_64-native-linuxapp-gcc/app/test > > > > EAL: Detected 8 lcore(s) > > EAL: Probing VFIO support... > > PMD: bnxt_rte_pmd_init() called for (null) > > EAL: PCI device 0000:03:00.0 on NUMA socket -1 > > EAL: probe driver: 8086:1533 rte_igb_pmd > > EAL: pci_map_resource(): > > cannot mmap(39, 0x7f1c51800000, 0x100000, 0x0): > > Invalid argument (0xffffffffffffffff) > > EAL: Error - exiting with code: 1 > > Cause: Requested device 0000:03:00.0 cannot be used > > > > The issue is exposed when the kernel is compiled with option > > CONFIG_IO_STRICT_DEVMEM turned on. > > > > This option is new from kernel 4.5 and is on by default in Fedora 24: > > > > config IO_STRICT_DEVMEM > > bool "Filter I/O access to /dev/mem" > > depends on STRICT_DEVMEM > > ---help--- > > > > If this option is disabled, you allow userspace (root) access > > to all io-memory regardless of whether a driver is actively > > using that range. Accidental access to this is obviously > > disastrous, but specific access can be used by people > > debugging kernel drivers. > > > > If this option is switched on, the /dev/mem file only allows > > userspace access to *idle* io-memory ranges (see /proc/iomem) > > This may break traditional users of /dev/mem (dosemu, legacy > > X, etc...) if the driver using a given range cannot be > > disabled. > > > > If in doubt, say Y. > > > > This issue doesn't occur with uio_pci_generic. > > > > John > > > > > Thanks for Pablo figuring out the details, and related config option, > otherwise I was digging same issue without success. > > Disabling following code in igb_uio makes it work again: > "pci_request_regions(dev, "igb_uio");" > > This call adds device bars as active resources, and with above config > option mmap fails for those addresses. > > uio_pci_generic already doesn't have this call, and I can send a patch > to remove this from igb_uio. > > BUT, I don't know why that call added at first place and concerned about > any corner case that requires this call. > Anybody out has/knows a reason to keep this call? > > Thanks, > ferruh > >
Another workaround to make this work is setting "iomem=relaxed" in the kernel parameters, to avoid recompiling the kernel with IO_STRICT_DEVMEM disabled. Thanks, Pablo
