Liu Yu wrote:
Hi guys,
In my kvm machine, I use serial as its default stdio.
But when display a number of characters, e.g. cat a big ascii file,
the serial always hangs as encount overwhelming interrupts, and then output a kernel log "serial8250: too much work for irq 42".
I found that the serial in qemu is primitive so that it generate a interrupt on every single character.
This make it easier to reach the threshold of reporting "too much work".
I had to use the patch below to get this issue walked arroud.
Have you guys ever met the serial hanging problem before?
We had that some times in the beginning while we brought up interrupts.
But since that time it did never occur again and I thought we fixed it.
Maybe your use case of catting a file to it is stressing it now to a new
extend triggering it again.
---
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index be95e55..af3e569 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -70,7 +70,7 @@ static unsigned int nr_uarts = CONFIG_SERIAL_8250_RUNTIME_UARTS;
#define DEBUG_INTR(fmt...) do { } while (0)
#endif
-#define PASS_LIMIT 256
+#define PASS_LIMIT 65535
/*
* We default to IRQ0 for the "no irq" hack. Some
Best Regards.
Yu
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--
Grüsse / regards,
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization
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