On Thu, 2 Jul 2015 11:32:52 +0200 "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: > On Thu, Jul 02, 2015 at 11:12:56AM +0200, Greg Kurz wrote: > > On Thu, 2 Jul 2015 08:01:28 +0200 > > "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote: ... > > > Yea, well - support for legacy BE guests on the new LE hosts is > > > exactly the motivation for this. > > > > > > I dislike it too, but there are two redeeming properties that > > > made me merge this: > > > > > > 1. It's a trivial amount of code: since we wrap host/guest accesses > > > anyway, almost all of it is well hidden from drivers. > > > > > > 2. Sane platforms would never set flags like VHOST_CROSS_ENDIAN_LEGACY - > > > and when it's clear, there's zero overhead (as some point it was > > > tested by compiling with and without the patches, got the same > > > stripped binary). > > > > > > Maybe we could create a Kconfig symbol to enforce point (2): prevent > > > people from enabling it e.g. on x86. I will look into this - but it can > > > be done by a patch on top, so I think this can be merged as is. > > > > > > > This cross-endian *oddity* is targeting PowerPC book3s_64 processors... I > > am not aware of any other users. Maybe create a symbol that would > > be only selected by PPC_BOOK3S_64 ? > > I think some ARM systems are trying to support cross-endian > configurations as well. > > Besides that, yes, this is more or less what I had in mind. Would something simple like this already do the job: diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig --- a/drivers/vhost/Kconfig +++ b/drivers/vhost/Kconfig @@ -35,6 +35,7 @@ config VHOST config VHOST_CROSS_ENDIAN_LEGACY bool "Cross-endian support for vhost" + depends on KVM_BOOK3S_64 || KVM_ARM_HOST default n ---help--- This option allows vhost to support guests with a different byte ? If that looks acceptable, I can submit a proper patch if you like. Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
