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Re: [Qemu-devel] [PATCH] block/nvme: Remove QEMU_PACKED from naturally a
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct |
Date: |
Mon, 25 Feb 2019 15:09:35 +0100 |
User-agent: |
Mutt/1.11.3 (2019-02-01) |
Am 25.02.2019 um 12:59 hat Thomas Huth geschrieben:
> 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 <address@hidden>
> Signed-off-by: Thomas Huth <address@hidden>
Thanks, applied to the block branch.
Though I'm not sure why a compiler should warn if packed and non-packed
result in the exact same layout anyway...
Kevin