linux-kernel - Re: [PATCH] Revert "arm64: Increase the max granular size"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <56EAD53C.80707@arm.com>
Date:	Thu, 17 Mar 2016 16:03:08 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Catalin Marinas <catalin.marinas@....com>,
	Timur Tabi <timur@...eaurora.org>
Cc:	Ganesh Mahendran <opensource.ganesh@...il.com>,
	Will Deacon <will.deacon@....com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	rrichter@...ium.com, tchalamarla@...ium.com,
	Shanker Donthineni <shankerd@...eaurora.org>,
	apinski@...ium.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] Revert "arm64: Increase the max granular size"

On 17/03/16 15:37, Catalin Marinas wrote:
> On Thu, Mar 17, 2016 at 09:49:51AM -0500, Timur Tabi wrote:

[...]

>> Keep in mind that on an ACPI system like ours, the boot loader (UEFI in our
>> case) configures the system extensively.  It does a lot of things that the
>> kernel would normally do on a device tree system.  For example, pin control
>> is handled completely by UEFI.  The kernel does not set the pin muxes or
>> GPIO directions.  That means we don't support dynamic pin muxing.  Before
>> the kernel is booted, the GPIO pins are fixed.
> 
> And that's great. But you are mistaken in thinking that DT requires lots
> of drivers in the kernel and prevents the firmware from doing sane
> stuff. DT rather gained additional features out of necessity since the
> firmware was not always doing a proper job at hardware initialisation.
> A DT-enabled kernel does not impose restrictions on such firmware
> features. With ACPI, the choice is not as wide and forces vendors to
> look into their firmware story from a different angle (until they figure
> the _DSD+PRP0001 out and we end up with DT emulated in ACPI).

Or even worse, perverting the couple of things that were actually OK in
ACPI by inventing a new layer of broken stuff:

http://thread.gmane.org/gmane.linux.ports.arm.msm/17828

Once we've reached that level, _DSD fells all nice and cuddly.

	M.
-- 
Jazz is not dead. It just smells funny...