On 2011-12-04 15:24, Michael S. Tsirkin wrote: > On Sun, Dec 04, 2011 at 02:22:12PM +0100, Jan Kiszka wrote: >> From: Jan Kiszka <jan.kis...@siemens.com> >> >> There is no point in pushing this burden to the devices, they may rather >> forget to call them (like intel-hda and ahci ATM). Instead, reset >> functions are now called from pci_device_reset and pci_bridge_reset. >> They do nothing if the MSI/MSI-X is not in use. >> >> CC: Alexander Graf <ag...@suse.de> >> CC: Gerd Hoffmann <kra...@redhat.com> >> CC: Isaku Yamahata <yamah...@valinux.co.jp> >> Signed-off-by: Jan Kiszka <jan.kis...@siemens.com> > > What makes me unhappy with this proposal is that msix_write_config, for > example, becomes in fact an internal interface. So devices should be > calling some functions like msix_init from msix.h, but not others like > msix_write_config. > > It used to be simple: devices should call msix_. > Now, how are devices to figure it out? > > E.g. the comment near msix_write_config says: > /* Handle MSI-X capability config write. */
That should be aligned to msi_write_config's comment. My goal is to reduce the number of calls devices have to do in order to use MSI. We have quite a few correct examples by now, so it should not be too hard to figure out what to do to use standard MSI[X] services. Maybe a PCI skeleton device model would help further. Or up-to-date documentation, thought that may be even harder. ;) > > This puts it at level 11 on Rusty's misuse scale: > Read the documentation and you will get it wrong. > > So I tried writing a wapper, something like pci_capability.h, that would > hide the detail and handle all capabilities seamlessly. Where I got > stuck was migration though, format is ordered so we can't just move the > fields around. So I decided to wait until we switch to an unordered > format, then it'll become easy. > > Thoughts? MSI-X save/restore is, well, unfortunate. Just like the whole PCI layer in this regard. But I don't think that should block this particular step as it frees device models from an unneeded burden. Jan
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