> -----Original Message----- > From: Frederico Cadete [mailto:frederico.cadete-...@oneaccess-net.com] > Sent: Tuesday, June 27, 2017 9:32 PM > To: yuanhan....@linux.intel.com; maxime.coque...@redhat.com; Tan, > Jianfeng > Cc: John Sucaet; dev@dpdk.org > Subject: Re: bug: virtio PMD sends malformed packets for 32-bit processes > on 64-bit kernel ... > > > > > > In that case I guess that the issue is that the conversion is > > > assuming > > > that on 32-bit apps only 4 bytes are necessary, even in the case of > > > virtio-pci and 64-bit physaddr. > > > > > > Would you say that this is how vring_desc's addr should be filled? > > > > > > | 32-bit app | 64-bit app | > > > ------------+-----------------------+ -----------------------+ > > > virtio-pci | buf_physaddr, 8 bytes | buf_physaddr, 8 bytes | > > > virtio-user | buf_addr, 4 bytes | buf_addr, 8 bytes | > > > > > > I believe that the issue is that after commit 260aae9a, for virtio- > > > pci > > > and 32-bit app it is taking 4 bytes instead of 8. > > Aha, yes, that's the issue! Great analysis. After Bruce's commit > > 586ec205bcbbb ("mbuf: fix 64-bit address alignment in 32-bit > > builds"), > > we can fix this issue by fetching 8 bytes at all cases. But > > unfortunately, that commit is not back-ported to v17.02.1. > > I don't see how changing the alignment of buf_physaddr allows fetching > 8 bytes in all cases, even in the case of 32-bit virtio-user where what > we need are 4 bytes from buf_addr. Am I missing something?
After that, | 4-byte buf_addr | 4-byte padding | 8-byte buf_physaddr| for 32-bit system, right? I would expect 4-byte padding are all-zero. So we can just fetch all first 8-byte outside. > > Besides, Bruce's patch changes the memory layout of rte_mbuf. A priori > that's not the kind I would like to find in an update of a stable > branch :) Yes, you are right. Stable branches won't accept such change. > > > > > I wonder if we can back-port Bruce's patch with a new patch to fix > > this > > problem? > > > > Any opinions from others? > > > > Thanks, > > Jianfeng > > > > > > > > > > > > > > > > > > > > > > Any suggestions on if and how this could be fixed? > > > > > > > > > > Meanwhile, the bug affects dpdk 17.05, 17.02.1 and master. > > > > > Users > > > > > not > > > > > requiring virtio-user support can avoid it by setting > > > > > CONFIG_VIRTIO_USER=n during compilation. > > > > > > > > > > Best regards, > > > > > Frederico Cadete