Hi. This is my first time trying to contribute to qemu. This patch
works correctly for architectures with the same bit-width, for example
32bit arm host and i386 user binary. Here is an example with the sg_simple2
executable from https://github.com/hreinecke/sg3_utils
32-bit ARM native:
strace -e trace=ioctl ./sg_simple2 /dev/sg0
ioctl(3, SG_GET_VERSION_NUM, [30536]) = 0
ioctl(3, SG_IO, {interface_id='S', dxfer_direction=SG_DXFER_FROM_DEV, cmd_len=6,
cmdp="\x12\x00\x00\x00\x60\x00", mx_sb_len=32, iovec_count=0, dxfer_len=96, timeout=20000, flags=0,
dxferp="\x05\x80\x00\x32\x5b\x00\x00\x00\x48\x4c\x2d\x44\x54\x2d\x53\x54\x42\x44\x2d\x52\x45\x20\x20\x57\x48\x31\x36\x4e\x53\x34\x30\x20"...,
status=0, masked_status=0, msg_status=0, sb_len_wr=0, sbp="", host_status=0, driver_status=0,
resid=0, duration=3, info=0}) = 0
Some of the INQUIRY command's results:
HL-DT-ST BD-RE WH16NS40 1.05 [wide=0 sync=0 cmdque=0 sftre=0]
ioctl(3, SG_IO, {interface_id='S', dxfer_direction=SG_DXFER_NONE, cmd_len=6,
cmdp="\x00\x00\x00\x00\x00\x00", mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000,
flags=0, status=0, masked_status=0, msg_status=0, sb_len_wr=0, sbp="", host_status=0,
driver_status=0, resid=0, duration=4, info=0}) = 0
Test Unit Ready successful so unit is ready!
+++ exited with 0 +++
i386 binary on 32-bit arm host:
strace -f -e trace=ioctl qemu/build/i386-linux-user/qemu-i386
sg3_utils/examples/sg_simple2 /dev/sg0
strace: Process 690 attached
[pid 689] ioctl(3, SG_GET_VERSION_NUM, [30536]) = 0
[pid 689] ioctl(3, SG_IO, {interface_id='S', dxfer_direction=SG_DXFER_FROM_DEV, cmd_len=6,
cmdp="\x12\x00\x00\x00\x60\x00", mx_sb_len=32, iovec_count=0, dxfer_len=96, timeout=20000, flags=0,
dxferp="\x05\x80\x00\x32\x5b\x00\x00\x00\x48\x4c\x2d\x44\x54\x2d\x53\x54\x42\x44\x2d\x52\x45\x20\x20\x57\x48\x31\x36\x4e\x53\x34\x30\x20"...,
status=0, masked_status=0, msg_status=0, sb_len_wr=0, sbp="", host_status=0, driver_status=0,
resid=0, duration=3, info=0}) = 0
Some of the INQUIRY command's results:
HL-DT-ST BD-RE WH16NS40 1.05 [wide=0 sync=0 cmdque=0 sftre=0]
[pid 689] ioctl(3, SG_IO, {interface_id='S', dxfer_direction=SG_DXFER_NONE, cmd_len=6,
cmdp="\x00\x00\x00\x00\x00\x00", mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000,
flags=0, status=0, masked_status=0, msg_status=0, sb_len_wr=0, sbp="", host_status=0,
driver_status=0, resid=0, duration=3, info=0}) = 0
Test Unit Ready successful so unit is ready!
[pid 690] +++ exited with 0 +++
+++ exited with 0 +++
However when I try i386 guest on x86_64 host, the cmdp bytes in the
first SG_IO call are zero, incorrectly. I assume that is because I need
to write a special ioctl handler. Is that correct? Should I be calling
lock_user(VERIFY_WRITE...) to copy the buffers over?