On 11/29/2014 12:42 AM, Thomas Monjalon wrote: > 2014-11-28 16:13, Jincheng Miao: >> 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. >>> Please, could you explain in which case CONFIG_PCI_IOV is defined? >>> The logic is a bit difficult to understand. >> 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.
I am not the expert on this, the only thing I know is: CONFIG_PCI_IOV is config switch for the I/O device virtualization, it will enable some SRIOV feature for PCI devices supports IO virtualization. It is defined since upstream kernel v2.6.30 (d1b054d). But as you said, function pci_num_vf() is stub-defined in kernel when CONFIG_PCI_IOV disabled. So checking CONFIG_PCI_IOV is meaningless for pci_num_vf(). For the function pci_num_vf(), I wrote it is defined since RHEL6.0. But after some searching, I found the earliest is RHEL5 Update9 kernel-devel-2.6.18-348.el5.x86_64.rpm. I think it should be modified to: ``` #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34) && \ - !defined(CONFIG_PCI_IOV) + (!(defined(RHEL_RELEASE_CODE) && \ + RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(5, 9))) ``` After that, if there is other distro need to be compatible, we could simply add condition bellow: (!(defined(OTHER_RELEASE_CODE) && OTHER_RELEASE_CODE >= OTHER_RELEASE_VERSION(X, Y))) Thanks for your patient for pointing out the issue of my patch. Jincheng Miao >> The logic of this patch is: >> #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34) && \ >> (!(defined(RHEL_RELEASE_CODE) && RHEL_RELEASE_CODE >= >> RHEL_RELEASE_VERSION(6, 0) && defined(CONFIG_PCI_IOV))) >> >> Firstly it detects kernel version, if it is less than 2.6.34, and it is >> not RHEL-specified, then define pci_num_vf(). >> >> Secondly, it deals with RHEL-specified. If it is RHEL6.0 or later, and >> CONFIG_PCI_IOV is defined. we should not define pci_num_vf(). If any of >> 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 error: >> ``` >> CC [M] >> /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: >> In function ?show_max_vfs?: >> /root/dpdk-source/build/build/lib/librte_eal/linuxapp/igb_uio/igb_uio.c:75: >> error: implicit declaration of function ?pci_num_vf? >> ``` > Thank you. Describing the problem is helpful for the commit log. > >> This problem is introduced by commit 11ba04265 >> >> commit 11ba04265cfd2a53c12c030fcaa5dfe7eed39a42 >> Author: Guillaume Gaudonville<guillaume.gaudonville at 6wind.com> >> Date: Wed Sep 3 10:18:23 2014 +0200 >> >> igb_uio: fix build on RHEL 6.3 >> >> - 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 >> >> Signed-off-by: Guillaume Gaudonville<guillaume.gaudonville at 6wind.com> >> Signed-off-by: David Marchand<david.marchand at 6wind.com> >> Signed-off-by: Thomas Monjalon<thomas.monjalon at 6wind.com> >> >> +#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 34) && \ >> + !defined(CONFIG_PCI_IOV) >> >> That is because longterm kernel 2.6.32.63 defined CONFIG_PCI_IOV, but it >> lacks pci_num_vf(), >> after above processing, pci_num_vf() is still not existed, then build fail. >> >> My patch could work around it, and can deal with RHEL-specified kernel. > Thanks, we just need to understand the matrix of combinations to be sure > it will be well maintained. >
