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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 10/11] vpci: Add initial support for virtual PCI bus topology
On 29.09.21 16:23, Jan Beulich wrote: > On 29.09.2021 15:16, Oleksandr Andrushchenko wrote: >> On 29.09.21 15:54, Jan Beulich wrote: >>> On 29.09.2021 13:56, Oleksandr Andrushchenko wrote: >>>> On 29.09.21 12:09, Jan Beulich wrote: >>>>> On 29.09.2021 11:03, Oleksandr Andrushchenko wrote: >>>>>> Sorry for top posting, but this is a general question on this >>>>>> patch/functionality. >>>>>> >>>>>> Do you see we need to gate all this with CONFIG_HAS_VPCI_GUEST_SUPPORT >>>>>> as this renders in somewhat dead code for x86 for now? I do think this >>>>>> still >>>>>> needs to be in the common code though. >>>>> I agree it wants to live in common code, but I'd still like the code to >>>>> not bloat x86 binaries. Hence yes, I think there want to be >>>>> "if ( !IS_ENABLED() )" early bailout paths or, whenever this isn't >>>>> possible without breaking the build, respective #ifdef-s. >>>> Then it needs to be defined as (xen/drivers/Kconfig): >>>> >>>> config HAS_VPCI_GUEST_SUPPORT >>>> # vPCI guest support is only enabled for Arm now >>>> def_bool y if ARM >>>> depends on HAS_VPCI >>>> >>>> Because it needs to be defined as "y" for Arm with vPCI support. >>>> >>>> Otherwise it breaks the PCI passthrough feature, e.g. it compiles, >>>> >>>> but the resulting binary behaves wrong. >>>> >>>> Do you see this as an acceptable solution? >>> Like all (or at least the majority) of other HAS_*, it ought to be >>> "select"-ed (by arm/Kconfig). Is there a reason this isn't possible? >>> (I don't mind the "depends on", as long as it's clear that it exists >>> solely to allow kconfig to warn about bogus "select"s.) >> There is yet no Kconfig exists (even for Arm) that enables HAS_VPCI, >> >> thus I can't do that at the moment even if I want to. Yes, this can be >> deferred >> >> to the later stage when we enable VPCI for Arm, bit this config option is >> still >> >> considered as "common code" as the functionality being added >> >> to the common code is just gated with CONFIG_HAS_VPCI_GUEST_SUPPORT. >> >> With this defined now and not later the code seems to be complete and more >> clean >> >> as it is seen what is this configuration option and how it is enabled and >> used in the >> >> code. >> >> So, I see no problem if it is defined in this Kconfig and evaluates to "n" >> for x86 >> >> and eventually will be "y" for Arm when it enables HAS_VPCI. > I'm afraid I don't view this as a reply reflecting that you have > understood what I'm asking for. The primary request is for there to > not be "def_bool y" but just "bool" accompanied by a "select" in > Arm's Kconfig. If HAS_VPCI doesn't exist as an option yet, simply > omit the (questionable) "depends on". I understood that, but was trying to make sure we don't miss this option while enabling vPCI on Arm, but ok, I'll have the following: config HAS_VPCI bool config HAS_VPCI_GUEST_SUPPORT bool depends on HAS_VPCI and select it for Arm xen/arch/arm/Kconfig > > Jan > PS: The more replies I get from you, the more annoying I find the > insertion of blank lines between every two lines of text. Blank > lines are usually used to separate paragraphs. If it is your mail > program which inserts these, can you please try to do something > about this? Thanks. > I first thought that this is how Thunderbird started showing my replies and was also curious about the distance between the lines which seemed to be as double-line, but I couldn't delete or edit those. I thought this is only visible to me... It came out that this was because of some Thunderbird settings which made my replies with those double-liners. Hope it is fixed now. I am really sorry about that and do understand how annoying it was. Best regards, Oleksandr
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