Alan Cox wrote:
On Sat, 12 Jan 2008 15:15:43 -0500
Benjamin LaHaise <bcrl@xxxxxxxxx> wrote:
When using kvm with a serial console, the serial driver will print out
"too much work for irq4" on any heavy activity (ie vi on a file repainting
the terminal). This message is entirely spurious, as output continues to
work fine. Remove the message as it corrupts screen output and is far too
easy to trigger.
NAK. This is a qemu/kvm emulation bug. The real check is there to catched
jammed IRQs and combined with the IRQ bug handling nowdays does actually
do the intended job.
Our serial port code (correctly) interprets a continuous stream of bytes
at an impossible bit rate as an error. KVM should be emulating to some
extent at least the timing on serial interfaces or using a virtualised
interface.
This is going to put trouble in other places unless, at least, it can be
turned off. The UART serial interface is heavily emulated as a console
interface without an actual serial port behind it, both in hardware and
software. Rates will typically vastly exceed real serial port rates,
especially emulating 16450 or 16550 (which is typical) which are limited
to 115200 bps.
-hpa
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