[Qemu-devel] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct

From: Thomas Huth <thuth@redhat.com>
To: qemu-devel@nongnu.org, Fam Zheng <fam@euphon.net>
Cc: qemu-block@nongnu.org, qemu-trivial@nongnu.org,
	Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Subject: [Qemu-devel] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct
Date: Mon, 25 Feb 2019 12:59:30 +0100	[thread overview]
Message-ID: <1551095970-14645-1-git-send-email-thuth@redhat.com> (raw)

The QEMU_PACKED is causing a compiler warning/error with GCC 9:

  CC      block/nvme.o
block/nvme.c: In function ‘nvme_create_queue_pair’:
block/nvme.c:209:22: error: taking address of packed member of
 ‘struct <anonymous>’ may result in an unaligned pointer value
 [-Werror=address-of-packed-member]
  209 |     q->sq.doorbell = &s->regs->doorbells[idx * 2 * s->doorbell_scale];

All members of the struct are naturally aligned, so there should
not be the need for QEMU_PACKED here, and the following QEMU_BUILD_BUG_ON
also ensures that there is no padding. Thus simply remove the QEMU_PACKED
here.

Buglink: https://bugs.launchpad.net/qemu/+bug/1817525
Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 block/nvme.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/nvme.c b/block/nvme.c
index b5952c9..6c2ce7d 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -82,7 +82,7 @@ typedef volatile struct {
     uint8_t  reserved1[0xec0];
     uint8_t  cmd_set_specfic[0x100];
     uint32_t doorbells[];
-} QEMU_PACKED NVMeRegs;
+} NVMeRegs;
 
 QEMU_BUILD_BUG_ON(offsetof(NVMeRegs, doorbells) != 0x1000);
 
-- 
1.8.3.1
