For usb-ehci in qemu, its caps just has read() operation,
the write() operation does not exist.
This cause a Segmentation fault when use usb-ehci device in ppc64
platform.
here is gdb output:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x3fffa7fcef20 (LWP 6793)]
0x00000000103f5244 in memory_region_oldmmio_write_accessor
(opaque=0x113e9e78, addr=9, value=0x3fffa7fce088,
size=1, shift=0, mask=255) at /home/Mike/qemu-impreza/memory.c:384
384 mr->ops->old_mmio.write[ctz32(size)](mr->opaque, addr, tmp);
(gdb) p *mr->ops
$1 = {read = @0x10716f68: 0x1020699c <ehci_caps_read>, write = 0,
endianness = DEVICE_LITTLE_ENDIAN, valid = {min_access_size = 1,
max_access_size = 4, unaligned = false, accepts = 0}, impl =
{min_access_size = 1, max_access_size = 1, unaligned = false},
old_mmio = {read = {0, 0, 0}, write = {0, 0, 0}}}
Becasue function write() of mr->ops has not been implement, in
function memory_region_dispatch_write(), it call
oldmmio write accessor, but at the same time old_mmio still not
been implement by default.
That is the root cause of the Segmentation fault.
To solve this problem, add empty function: ehci_caps_write()
Signed-off-by: Mike Qiu <qiud...@linux.vnet.ibm.com>
---
hw/usb/hcd-ehci.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 67e4b24..6c8a439 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -1072,6 +1072,12 @@ static void ehci_port_write(void *ptr, hwaddr addr,
trace_usb_ehci_portsc_change(addr + s->portscbase, addr >> 2, *portsc,
old);
}
+static void ehci_caps_write(void *ptr, hwaddr addr, uint64_t val,
+ unsigned size)
+{
+ /* nothing */
+}
+
static void ehci_opreg_write(void *ptr, hwaddr addr,
uint64_t val, unsigned size)
{
@@ -2380,6 +2386,7 @@ static void ehci_frame_timer(void *opaque)
static const MemoryRegionOps ehci_mmio_caps_ops = {
.read = ehci_caps_read,
+ .write = ehci_caps_write,
.valid.min_access_size = 1,
.valid.max_access_size = 4,
.impl.min_access_size = 1,
--
1.7.10.1
