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From: Kevin Wolf <kwolf@redhat.com>
To: Thomas Huth <thuth@redhat.com>
Cc: qemu-devel@nongnu.org, Fam Zheng <fam@euphon.net>,
	qemu-block@nongnu.org, qemu-trivial@nongnu.org,
	Max Reitz <mreitz@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Subject: Re: [Qemu-trivial] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct
Date: Mon, 25 Feb 2019 15:09:35 +0100	[thread overview]
Message-ID: <20190225140935.GE6320@linux.fritz.box> (raw)
In-Reply-To: <1551095970-14645-1-git-send-email-thuth@redhat.com>

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 <sathnaga@linux.vnet.ibm.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>

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


WARNING: multiple messages have this Message-ID (diff)
From: Kevin Wolf <kwolf@redhat.com>
To: Thomas Huth <thuth@redhat.com>
Cc: qemu-devel@nongnu.org, Fam Zheng <fam@euphon.net>,
	qemu-block@nongnu.org, qemu-trivial@nongnu.org,
	Max Reitz <mreitz@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct
Date: Mon, 25 Feb 2019 15:09:35 +0100	[thread overview]
Message-ID: <20190225140935.GE6320@linux.fritz.box> (raw)
In-Reply-To: <1551095970-14645-1-git-send-email-thuth@redhat.com>

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 <sathnaga@linux.vnet.ibm.com>
> Signed-off-by: Thomas Huth <thuth@redhat.com>

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

  parent reply	other threads:[~2019-02-25 14:09 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-25 11:59 [Qemu-trivial] [PATCH] block/nvme: Remove QEMU_PACKED from naturally aligned NVMeRegs struct Thomas Huth
2019-02-25 11:59 ` [Qemu-devel] " Thomas Huth
2019-02-25 12:51 ` [Qemu-trivial] " Peter Maydell
2019-02-25 12:51   ` [Qemu-devel] " Peter Maydell
2019-02-25 14:09 ` Kevin Wolf [this message]
2019-02-25 14:09   ` Kevin Wolf
2019-02-25 14:30   ` [Qemu-trivial] " Peter Maydell
2019-02-25 14:30     ` [Qemu-devel] " Peter Maydell
2019-02-25 15:28     ` [Qemu-trivial] " Thomas Huth
2019-02-25 15:28       ` [Qemu-devel] " Thomas Huth

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