On Mon, Oct 05, 2015 at 02:09:32PM +0300, Avi Kivity wrote: > On 10/05/2015 01:57 PM, Greg KH wrote: > >On Mon, Oct 05, 2015 at 01:48:39PM +0300, Vlad Zolotarov wrote: > >> > >>On 10/05/15 10:56, Greg KH wrote: > >>>On Mon, Oct 05, 2015 at 10:41:39AM +0300, Vlad Zolotarov wrote: > >>>>>>+struct msix_info { > >>>>>>+ int num_irqs; > >>>>>>+ struct msix_entry *table; > >>>>>>+ struct uio_msix_irq_ctx { > >>>>>>+ struct eventfd_ctx *trigger; /* MSI-x vector to > >>>>>>eventfd */ > >>>>>Why are you using eventfd for msi vectors? What's the reason for > >>>>>needing this? > >>>>A small correction - for MSI-X vectors. There may be only one MSI vector > >>>>per > >>>>PCI function and if it's used it would use the same interface as a legacy > >>>>INT#x interrupt uses at the moment. > >>>>So, for MSI-X case the reason is that there may be (in most cases there > >>>>will > >>>>be) more than one interrupt vector. Thus, as I've explained in a PATCH1 > >>>>thread we need a way to indicated each of them separately. eventfd seems > >>>>like a good way of doing so. If u have better ideas, pls., share. > >>>You need to document what you are doing here, I don't see any > >>>explaination for using eventfd at all. > >>> > >>>And no, I don't know of any other solution as I don't know what you are > >>>trying to do here (hint, the changelog didn't document it...) > >>> > >>>>>You haven't documented how this api works at all, you are going to have > >>>>>to a lot more work to justify this, as this greatly increases the > >>>>>complexity of the user/kernel api in unknown ways. > >>>>I actually do documented it a bit. Pls., check PATCH3 out. > >>>That provided no information at all about how to use the api. > >>> > >>>If it did, you would see that your api is broken for 32/64bit kernels > >>>and will fall over into nasty pieces the first time you try to use it > >>>there, which means it hasn't been tested at all :( > >>It has been tested of course ;) > >>I tested it only in 64 bit environment however where both kernel and user > >>space applications were compiled on the same machine with the same compiler > >>and it could be that "int" had the same number of bytes both in kernel and > >>in user space application. Therefore it worked perfectly - I patched DPDK to > >>use the new uio_pci_generic MSI-X API to test this and I have verified that > >>all 3 interrupt modes work: MSI-X with SR-IOV VF device in Amazon EC2 guest > >>and INT#x and MSI with a PF device on bare metal server. > >> > >>However I agree using uint32_t for "vec" and "fd" would be much more > >>correct. > >I don't think file descriptors are __u32 on a 64bit arch, are they? > > > >And NEVER use the _t types in kernel code, the namespaces is all wrong > >and it is not applicable for us, sorry. > > Wasn't the real reason that they aren't defined (or reserved) by C89, and > therefore could clash with a user identifier, rather than some inherent > wrongness?
Kind of, my memory is vague. There's a great rant from Linus about why they don't work in the kernel somewhere in the lkml archives... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/