Hi, > On 8 Apr 2021, at 7:00 am, Jan Beulich <jbeul...@suse.com> wrote: > > On 07.04.2021 20:06, Julien Grall wrote: >> Hi Jan, >> >> On 06/04/2021 16:25, Jan Beulich wrote: >>> On 06.04.2021 16:30, Julien Grall wrote: >>>> Hi Roger, >>>> >>>> On 06/04/2021 15:13, Roger Pau Monné wrote: >>>>> On Tue, Apr 06, 2021 at 12:39:11PM +0100, Rahul Singh wrote: >>>>>> MSI support is not implemented for ARM architecture but it is enabled >>>>>> for x86 architecture and referenced in common passthrough/pci.c code. >>>>>> >>>>>> Therefore introducing the new flag to gate the MSI code for ARM in >>>>>> common code to avoid compilation error when HAS_PCI is enabled for ARM. >>>>> >>>>> Is such option really interesting long term? >>>>> >>>>> IIRC PCI Express mandates MSI support, at which point I don't see much >>>>> value in being able to compile out the MSI support. >>>> >>>> I am pretty sure there are board out with PCI support but no MSI >>>> support. Anyway, even if the spec may mandate it... >>>> >>>>> >>>>> So while maybe helpful for Arm PCI efforts ATM, I'm not sure it >>>>> warrants a Kconfig option, I would rather see Arm introduce dummy >>>>> helpers for the missing functionality, even if unimplemented at the >>>>> moment. >>>> >>>> ... from my understanding, most of (if not all) the MSI code is not very >>>> useful on Arm when using the GICv3 ITS. >>>> >>>> The GICv3 ITS will do the isolation for you and therefore we should not >>>> need to keep track of the state at the vPCI level. >>> >>> But that's then not "has PCI MSI" but "need to intercept PCI MSI >>> accesses", i.e. I don't think the Kconfig option is correctly >>> named. If a device with MSI support is used, you can't make that >>> MSI support go away, after all. >> >> That's actually a good point. Rahul, do you think the config can be >> renamed to something like CONFIG_PCI_MSI_NEED_INTERCEPT? > > Minor remark: In this name I'd be inclined to suggest to omit NEED. >
OK . I will use the name CONFIG_PCI_MSI_INTERCEPT and will send next version of the patch. Regards, Rahul > Jan
