On 3/4/19 8:11 PM, Eric Blake wrote:
On 3/4/19 2:42 AM, Marcel Apfelbaum wrote:
Configuring QEMU with:
../configure --cc=clang --enable-rdma
Leads to compilation error:
CC migration/rdma.o
CC migration/block.o
qemu/migration/rdma.c:3615:58: error: taking address of packed
member 'rkey' of class or structure
'RDMARegisterResult' may result in an unaligned pointer value
[-Werror,-Waddress-of-packed-member]
(uintptr_t)host_addr, NULL,
®_result->rkey,
^~~~~~~~~~~~~~~~
This is a false warning; even if RDMARegisterResult is "packed", rkey
is the first field so is guaranteed to be aligned.
Not so. If you packed struct, gcc is free to abut that struct next to
some other unaligned field in a larger struct:
https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg06743.html
I wasn't referring to general case, but to this specific case. Actually
gcc does not complain, only clang.
Anyway, Dave's suggestion is clean and works for me.
Thanks,
Marcel
Fix it by disabling the warning only for this instance.
Ignoring the bug is not the same as fixing the bug. You need to
rework this, as the compiler warning is not a false negative.
Signed-off-by: Marcel Apfelbaum <[email protected]>
---
migration/rdma.c | 3 +++
1 file changed, 3 insertions(+)
