From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Fri, 26 Apr 2013 14:33:59 +0200 Subject: [PATCH 0/2] Early printk support for virtio console devices. In-Reply-To: References: <1366974299-17877-1-git-send-email-pranavkumar@linaro.org> Message-ID: <1577576.O1Cm2pf5KD@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Friday 26 April 2013 17:36:16 Anup Patel wrote: > On 26 April 2013 17:03, Peter Maydell wrote: > > On 26 April 2013 12:19, Alexander Graf wrote: > >> MMIO registers are handled by a different layer than the virtio > >> console itself. After the virtio refactoring in QEMU, they will > >> be completely separate drivers. > > > > Good point -- we don't really want to be mixing up the > > transport and the backend. You can see it in the kvmtool > > patch, in fact -- it introduces an "if this is virtio-console" > > special case into the mmio.c file which previously was > > entirely backend agnostic. > > Well, we can always have virtio device specific config registers > handle by virtio device backends and generic virtio config register > handled by transport. > > kvmtool patch is hacky because it does not provide virtio device > specific config read/write callbacks. Couldn't kvmtool implement the interface used by smh_printch() for early output instead? Or if that's not a fitting inteface, maybe a psci call for writing a character to the console? Arnd