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[109.190.92.136]) by mx.google.com with ESMTPSA id ry19sm15694643wjb.3.2014.11.28.08.43.10 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 28 Nov 2014 08:43:11 -0800 (PST) From: Thomas Monjalon To: Jincheng Miao Date: Fri, 28 Nov 2014 17:42:48 +0100 Message-ID: <3179225.WT7VCi68g0@xps13> Organization: 6WIND User-Agent: KMail/4.14.3 (Linux/3.17.4-1-ARCH; KDE/4.14.3; x86_64; ; ) In-Reply-To: <54782EB5.7060409@redhat.com> References: <1414741039-3531-1-git-send-email-jmiao@redhat.com> <7579030.6nSHmmQ36o@xps13> <54782EB5.7060409@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH v2 1/2] igb_uio: compatible with upstream longterm kernel and RHEL6 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Nov 2014 16:43:16 -0000 2014-11-28 16:13, Jincheng Miao: >=20 > On 11/28/2014 01:01 AM, Thomas Monjalon wrote: > > 2014-10-31 15:37, Jincheng Miao: > >> Function pci_num_vf() is introduced from upstream linux-2.6.34. So= > >> this patch make compatible with longterm kernel linux-2.6.32.63. > >> > >> For RHEL6's kernel, although it is based on linux-2.6.32, it has > >> pci_num_vf() implementation. As the same with commit 11ba0426, > >> pci_num_vf() is defined from RHEL6. So we should check the macro > >> RHEL_RELEASE_CODE to consider this situation. > >=20 > > Please, could you explain in which case CONFIG_PCI_IOV is defined? > > The logic is a bit difficult to understand. >=20 > Yep, there is a little confusion for pci_num_vf(): > 1. it is available when CONFIG_PCI_IOV is defined. > 2. it is introduced from upstream kernel v2.6.34 (fb8a0d9) > 3. it is implemented from RHEL6.0, although the kernel version is 2.6= .32. Sorry, you didn't described when CONFIG_PCI_IOV is defined. Is it defined since 2.6.34 upstream? In lower stable versions? Is it defined since RHEL 6.0? Why checking CONFIG_PCI_IOV is not sufficient? When pci_num_vf will be backported in other distributions, we will have= to tune this check and clearly understand what was the situation. > The logic of this patch is: > #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34) && \ > (!(defined(RHEL_RELEASE_CODE) && RHEL_RELEASE_CODE >=3D=20 > RHEL_RELEASE_VERSION(6, 0) && defined(CONFIG_PCI_IOV))) >=20 > Firstly it detects kernel version, if it is less than 2.6.34, and it = is=20 > not RHEL-specified, then define pci_num_vf(). >=20 > Secondly, it deals with RHEL-specified. If it is RHEL6.0 or later, an= d=20 > CONFIG_PCI_IOV is defined. we should not define pci_num_vf(). If any = of=20 > these conditions is not reached, pci_num_vf() should be defined. I can read the check but I don't know why CONFIG_PCI_IOV is checked in = the RHEL case. > Some days ago, I setup dpdk for longterm kernel 2.6.32.63, and got er= ror: > ``` > CC [M]=20 > /root/dpdk-source/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio= .o > /root/dpdk-source/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio= .c:=20 > In function =E2=80=98show_max_vfs=E2=80=99: > /root/dpdk-source/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio= .c:75:=20 > error: implicit declaration of function =E2=80=98pci_num_vf=E2=80=99 > ``` Thank you. Describing the problem is helpful for the commit log. =20 > This problem is introduced by commit 11ba04265 >=20 > commit 11ba04265cfd2a53c12c030fcaa5dfe7eed39a42 > Author: Guillaume Gaudonville > Date: Wed Sep 3 10:18:23 2014 +0200 >=20 > igb_uio: fix build on RHEL 6.3 >=20 > - pci_num_vf() is already defined in RHEL 6 > - pci_intx_mask_supported is already defined in RHEL 6.3 > - pci_check_and_mask_intx is already defined in RHEL 6.3 >=20 > Signed-off-by: Guillaume Gaudonville > Signed-off-by: David Marchand > Signed-off-by: Thomas Monjalon >=20 > +#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34) && \ > + !defined(CONFIG_PCI_IOV) >=20 > That is because longterm kernel 2.6.32.63 defined CONFIG_PCI_IOV, but= it=20 > lacks pci_num_vf(), > after above processing, pci_num_vf() is still not existed, then build= fail. >=20 > My patch could work around it, and can deal with RHEL-specified kerne= l. Thanks, we just need to understand the matrix of combinations to be sur= e it will be well maintained. --=20 Thomas