Make QEMU consistently report write caching support for emulated IDE

drives to fix a hang during SLES 9 HVM guest installation.

Without this, the SLES 9 installer kernels (32 and 64 bit) were
getting inconsistent information from QEMU as to whether the
(emulated) IDE drives support write caching (which they do).  So part
of the kernel thought write caching was enabled (and enabled the usage
of barrier writes) and part of it didn't, which triggered a bug in
which the same barrier write is submitted over and over again ...

Fixed by setting another bit in the WIN_IDENTIFY (IDE drive "identify"
command) response to indicate we really, truly support write caching.

Signed-off-by: David Lively <dlively@virtualiron.com>
Signed-off-by: Ben Guthro <bguthro@virtualiron.com>

diff --git a/tools/ioemu/hw/ide.c b/tools/ioemu/hw/ide.c
index f681236b248ba43c77776984d45a3a6baffb3b58..3b138c76e4b75938c5f2d52c9a705d5da05aa862 100644 (file)
--- a/tools/ioemu/hw/ide.c
+++ b/tools/ioemu/hw/ide.c
@@ -596,7 +596,8 @@ static void ide_identify(IDEState *s)
     /* 13=flush_cache_ext,12=flush_cache,10=lba48 */
     put_le16(p + 83, (1 << 14) | (1 << 13) | (1 <<12) | (1 << 10));
     put_le16(p + 84, (1 << 14));
-    put_le16(p + 85, (1 << 14));
+    /* 14=nop 5=write_cache */
+    put_le16(p + 85, (1 << 14) | (1 << 5));
     /* 13=flush_cache_ext,12=flush_cache,10=lba48 */
     put_le16(p + 86, (1 << 14) | (1 << 13) | (1 <<12) | (1 << 10));
     put_le16(p + 87, (1 << 14));