Re: [PATCH v5 2/3] ACPI: allow longer device IDs

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Alexander Graf <graf@amazon.com>
Cc: Len Brown <lenb@kernel.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-crypto@vger.kernel.org, linux-acpi@vger.kernel.org,
	linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v5 2/3] ACPI: allow longer device IDs
Date: Sun, 27 Feb 2022 13:43:48 +0100	[thread overview]
Message-ID: <YhtyBHUyFysmZ9bC@zx2c4.com> (raw)
In-Reply-To: <0c73d29e-e558-efb9-d0d7-c612b2bb7e90@amazon.com>

Hi Alex,

On Sun, Feb 27, 2022 at 12:42:03PM +0100, Alexander Graf wrote:
> > To allow device drivers to match identifiers that exceed the 9 byte
> > limit, this simply ups the length to 16, just like it was before the
> > aforementioned commit. Empirical testing indicates that this
> 
> 
> This is only true for 64bit systems where padding automatically bloated 
> to 9 byte array to 16. I still believe the patch is fine as it is, but 
> there will be minor .rodata overhead on 32bit targets which you may want 
> to quantify in the patch description.

Good point. So I just tried this out with a 32-bit i686 kernel and the
results are the same again for the size of vmlinux. I then ran `objdump
--headers` and looked at the size of the .rodata section, where it's
also the same. I'm not quite sure what to make of this, as it's not what
I was expecting, but I think I tested it right. So maybe we're lucky
here?

Jason