From: Christoph Hellwig <hch@infradead.org>
To: Lukas Wunner <lukas@wunner.de>
Cc: Christoph Hellwig <hch@infradead.org>,
Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>,
linux-pci@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Bjorn Helgaas <bhelgaas@google.com>,
Dan Williams <dan.j.williams@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ilpo Jarvinen <ilpo.jarvinen@linux.intel.com>,
Keith Busch <kbusch@kernel.org>, Marek Behun <marek.behun@nic.cz>,
Pavel Machek <pavel@ucw.cz>, Randy Dunlap <rdunlap@infradead.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Stuart Hayes <stuart.w.hayes@gmail.com>
Subject: Re: [PATCH v3 3/3] PCI/NPEM: Add _DSM PCIe SSD status LED management
Date: Mon, 8 Jul 2024 03:14:44 -0700 [thread overview]
Message-ID: <Zou8FJLJ-3H7CInO@infradead.org> (raw)
In-Reply-To: <Zof-P7jNmoLvJTF-@wunner.de>
On Fri, Jul 05, 2024 at 04:07:59PM +0200, Lukas Wunner wrote:
> On Fri, Jul 05, 2024 at 06:04:39AM -0700, Christoph Hellwig wrote:
> > > +struct dsm_output {
> > > + u16 status;
> > > + u8 function_specific_err;
> > > + u8 vendor_specific_err;
> > > + u32 state;
> > > +} __packed;
> >
> > This structure is naturally aligned, so no need for the __packed.
>
> Isn't the compiler free to insert padding wherever it sees fit?
In terms of the standard: yes. It could even reorder members. In
terms of not breaking the Linux kernel (or other low-level software)
left, right and center: no.
> structs passed to ACPI firmware would no longer comply with the
> spec-prescribed layout then and declaring them __packed seems to be
> the only way to ensure that doesn't happen.
Take a look at just about any driver, file system or network protocol.
next prev parent reply other threads:[~2024-07-08 10:14 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-05 12:54 [PATCH v3 0/3] PCIe Enclosure LED Management Mariusz Tkaczyk
2024-07-05 12:54 ` [PATCH v3 1/3] leds: Init leds class earlier Mariusz Tkaczyk
2024-07-05 12:58 ` Christoph Hellwig
2024-07-05 12:54 ` [PATCH v3 2/3] PCI/NPEM: Add Native PCIe Enclosure Management support Mariusz Tkaczyk
2024-07-05 13:02 ` Christoph Hellwig
2024-07-05 13:22 ` Mariusz Tkaczyk
2024-07-05 13:29 ` Christoph Hellwig
2024-07-06 4:11 ` kernel test robot
2024-07-08 11:33 ` Ilpo Järvinen
2024-07-08 14:24 ` Mariusz Tkaczyk
2024-07-08 16:13 ` Ilpo Järvinen
2024-07-08 14:27 ` Lukas Wunner
2024-07-05 12:54 ` [PATCH v3 3/3] PCI/NPEM: Add _DSM PCIe SSD status LED management Mariusz Tkaczyk
2024-07-05 13:04 ` Christoph Hellwig
2024-07-05 14:07 ` Lukas Wunner
2024-07-08 10:14 ` Christoph Hellwig [this message]
2024-07-08 11:39 ` Ilpo Järvinen
2024-07-05 19:11 ` [PATCH v3 0/3] PCIe Enclosure LED Management stuart hayes
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