On Sat, Jan 07, 2012 at 06:27:06PM +0000, Julian Pidancet wrote:
On Thu, Jan 5, 2012 at 12:44 AM, Kevin O'Connor kevin@koconnor.net wrote:
Is the issue that writes to 0x402 are causing an issue on Xen, or just that you don't see the debug output?
What's the origin of 0xe9 - is it a "standard" for debug output? What does Xen do today on writes to 0xe9?
Xen has some sort of ring buffer similar to the linux one, that you can access using the xl dmesg command. Every guest access to the 0xe9 port is trapped by the hypervisor which appends the characters to the ring buffer. I doubt 0x402 does anything on Xen, aside from beeing trapped in qemu if configured correctly, but I havn't tried.
If you really want this, I'm okay with a patch that introduces CONFIG_DEBUG_PORT, and has Kconfig do all the magic of selecting the preferred debug port.
That okay?
-Kevin
Fine by me. I will prepare a patch soon.
Thanks.
Julian On Jan 7, 2012 9:31 PM, "Kevin O'Connor" kevin@koconnor.net wrote:
On Sat, Jan 07, 2012 at 06:27:06PM +0000, Julian Pidancet wrote:
On Thu, Jan 5, 2012 at 12:44 AM, Kevin O'Connor kevin@koconnor.net
wrote:
Is the issue that writes to 0x402 are causing an issue on Xen, or just that you don't see the debug output?
What's the origin of 0xe9 - is it a "standard" for debug output? What does Xen do today on writes to 0xe9?
Xen has some sort of ring buffer similar to the linux one, that you can access using the xl dmesg command. Every guest access to the 0xe9 port is trapped by the hypervisor which appends the characters to the ring buffer. I doubt 0x402 does anything on Xen, aside from beeing trapped in qemu if configured correctly, but I havn't tried.
If you really want this, I'm okay with a patch that introduces CONFIG_DEBUG_PORT, and has Kconfig do all the magic of selecting the preferred debug port.
That okay?
-Kevin
-
Julian Pidancet -
Kevin O'Connor