From mboxrd@z Thu Jan 1 00:00:00 1970 From: anup@brainfault.org (Anup Patel) Date: Wed, 1 May 2013 12:23:49 +0530 Subject: [PATCH 0/2] Early printk support for virtio console devices. In-Reply-To: <87sj27xxjr.fsf@rustcorp.com.au> References: <1366974299-17877-1-git-send-email-pranavkumar@linaro.org> <87obcyc9sh.fsf@rustcorp.com.au> <336C59AA-D5D7-472E-A8DA-EEB413DD6C68@suse.de> <87sj27xxjr.fsf@rustcorp.com.au> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, May 1, 2013 at 7:37 AM, Rusty Russell wrote: > Alexander Graf writes: >> There are not device specific registers in >> virtio-console. Virtio-console lives behind a virtio bus which doesn't >> know what these registers are. > > You're not going to make coherent arguments without reading that actual > patch we're discussing. And you're going to just waste everyone else's > time. > >> Even if you shove it into config space, > > Which is what the patch does... > >> it'd be broken because config access happens without intercepts on >> some platforms. > > But people keep assuming it, which is one reason virtio_ccw switched > from passive lguest-style config to active. Only lguest and the old kvm > virtio use it, and lguest can change. > > An emergency output is a reasonable idea, and this is a reasonable > implementation. The question is practical: will it be used? Because we > don't implement reasonable ideas which aren't going to be used. We are already using it for Guest bring-up on APM ARM64 board using KVMTOOL and so far it has been really helpful in debugging KVM ARM64 guest issues. Also, this is a very useful debugging method for Guest bring-up on other architectures supported by KVM and other Hypervisors that support VirtIO. > > Cheers, > Rusty. > _______________________________________________ > kvmarm mailing list > kvmarm at lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm Regards, Anup