mirror of
https://abf.rosa.ru/djam/kernel-xen.git
synced 2025-02-23 07:42:46 +00:00
28 lines
1.1 KiB
Text
28 lines
1.1 KiB
Text
From: jbeulich@novell.com
|
|
Subject: Xen: improve floppy behavior
|
|
Patch-mainline: n/a
|
|
References: bnc#584216
|
|
|
|
Timing is significantly different from native both because Xen traps
|
|
I/O port accesses and using DMA not being possible (without intrusive
|
|
changes). Due to the overhead of trapped port accesses, I/O is already
|
|
slow enough (and Xen doesn't run on very old hardware anyway), so the
|
|
situation can easily be improved by not enforcing REALLY_SLOW_IO.
|
|
|
|
This doesn't completely address the issue - Xen just cannot guarantee
|
|
scheduling of a particular vCPU with a maximum latency of about 80us
|
|
(needed for the default FIFO threshold value of 10). The only complete
|
|
solution would require making ISA DMA usable on Xen.
|
|
|
|
--- sle11sp1-2010-03-01.orig/drivers/block/floppy.c 2009-12-03 04:51:21.000000000 +0100
|
|
+++ sle11sp1-2010-03-01/drivers/block/floppy.c 2010-03-05 09:16:48.000000000 +0100
|
|
@@ -147,7 +147,9 @@
|
|
#define FLOPPY_SANITY_CHECK
|
|
#undef FLOPPY_SILENT_DCL_CLEAR
|
|
|
|
+#ifndef CONFIG_XEN
|
|
#define REALLY_SLOW_IO
|
|
+#endif
|
|
|
|
#define DEBUGT 2
|
|
#define DCL_DEBUG /* debug disk change line */
|