[v2] ide:do nothing for identify cmd if no any device attached

[PATCH v2] ide:do nothing for identify cmd if no any device attached

zhaoxin\RockCuioc posted 1 patch 3 years, 8 months ago

Diff against v1 v1
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Test docker-quick@centos7 passed

Test docker-mingw@fedora passed

Test checkpatch passed

Test FreeBSD passed

Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20200820070240.3970-1-RockCui-oc@zhaoxin.com

Maintainers: John Snow <jsnow@redhat.com>

hw/ide/core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

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[PATCH v2] ide:do nothing for identify cmd if no any device attached

Posted by zhaoxin\RockCuioc 3 years, 8 months ago

v1 -> v2:
    fix codestyle checked by checkpatch.pl

This patch is for avoiding win7 IDE driver polling 0x1f7 when
no any device attached. During Win7 VM boot procedure, if use virtio for
disk and there is no any device be attached on hda & hdb, the win7 IDE driver
would poll 0x1f7 for a while. This action may be stop windows LOGO atomic for
a while too on a poor performance CPU.

Signed-off-by: zhaoxin\RockCuioc <RockCui-oc@zhaoxin.com>
---
 hw/ide/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index d997a78e47..26d86f4b40 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -2073,8 +2073,9 @@ void ide_exec_cmd(IDEBus *bus, uint32_t val)
     s = idebus_active_if(bus);
     trace_ide_exec_cmd(bus, s, val);
 
-    /* ignore commands to non existent slave */
-    if (s != bus->ifs && !s->blk) {
+    /* ignore commands if no any device exist or non existent slave */
+    if ((!bus->ifs[0].blk && !bus->ifs[1].blk) ||
+        (s != bus->ifs && !s->blk)) {
         return;
     }
 
-- 
2.17.1