On Wed, Apr 17, 2019 at 10:41:37AM +0100, Russell King wrote: > On Sun, Apr 14, 2019 at 10:51:09PM -0700, Christoph Hellwig wrote: > > On Sat, Apr 13, 2019 at 06:30:52PM +0200, Heinrich Schuchardt wrote: > > > This patch avoids > > > ERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined! > > > observed when compiling v4.19.34. > > > > > > The xen-privcmd driver, which can be modular, calls set_pte_at() > > > which in turn may call __sync_icache_dcache(). > > > > Maybe that really is a sign that it should not be modular.. > > This issue has been discussed several times, and this URL gives a list > of all messages on linux-arm-kernel that mention __sync_icache_dcache: > > https://archive.armlinux.org.uk/lurker/search/20380101.000000.00000000@ml:linux-arm-kernel,sb:__sync_icache_dcache.en.html > > At the beginning of March, Boris Ostrovsky pointed that another solution > is available that does not need architecture private symbols to be > exported. > > Since I've already said in a previous thread that I don't want this > function exported, it seems the way forward is pretty obvious. Arnd submitted a patch, not sure what happened to it: https://lore.kernel.org/lkml/20190304204826.2414365-1-arnd@xxxxxxxx/ I think this boils down to whether set_pte_at() is allowed to be called from loadable modules. If yes, __sync_icache_dcache() needs exporting, otherwise Arnd's patch makes the relevant code built-in (and, if merged, I'm happy to revert the similar export on arm64). -- Catalin
