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Tue, 11 Jul 2017 09:56:15 +0800
From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>, "dev@dpdk.org"
<dev@dpdk.org>
Thread-Topic: [dpdk-dev] [RFC] pci: force address of mappings in secondary
process
Thread-Index: AQHS+eLgyG6dcA8FKUmPJC0hVH7QXaJN3UYw
Date: Tue, 11 Jul 2017 01:56:15 +0000
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References: <20170711011242.4606-1-stephen@networkplumber.org>
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Subject: Re: [dpdk-dev] [RFC] pci: force address of mappings in secondary
process
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> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Stephen
> Hemminger
> Sent: Tuesday, July 11, 2017 9:13 AM
> To: dev@dpdk.org
> Cc: Stephen Hemminger
> Subject: [dpdk-dev] [RFC] pci: force address of mappings in secondary
> process
>=20
> The PCI memory resources in the secondary process should be in
> the exact same location as the primary process. Otherwise
> there is a risk of a stray pointer.
>=20
> Not sure if this is right, but it looks like a potential
> problem.
>=20
> ---
> lib/librte_eal/common/eal_common_pci_uio.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/lib/librte_eal/common/eal_common_pci_uio.c
> b/lib/librte_eal/common/eal_common_pci_uio.c
> index 367a6816dcb8..2156b1a436c4 100644
> --- a/lib/librte_eal/common/eal_common_pci_uio.c
> +++ b/lib/librte_eal/common/eal_common_pci_uio.c
> @@ -77,7 +77,7 @@ pci_uio_map_secondary(struct rte_pci_device *dev)
>=20
> void *mapaddr =3D pci_map_resource(uio_res-
> >maps[i].addr,
> fd, (off_t)uio_res->maps[i].offset,
> - (size_t)uio_res->maps[i].size, 0);
> + (size_t)uio_res->maps[i].size,
> MAP_FIXED);
> /* fd is not needed in slave process, close it */
> close(fd);
> if (mapaddr !=3D uio_res->maps[i].addr) {
> --
> 2.11.0
+1 for this RFC. I also once encounter such problem, and I use the same way=
to solve it. The addr parameter of mmap() syscall is only a hint instead o=
f a must even the VMA is not occupied yet.
Thanks,
Jianfeng