On Mon, Feb 10, 2014 at 05:12:24PM +0100, Albert ARIBAUD wrote:
Hi Måns,
On Mon, 10 Feb 2014 15:14:49 +0000, Måns Rullgård mans@mansr.com wrote:
Albert ARIBAUD albert.u.boot@aribaud.net writes:
Hi Tom,
On Mon, 10 Feb 2014 08:21:39 -0500, Tom Rini trini@ti.com wrote:
On Mon, Feb 10, 2014 at 10:24:47AM +0100, Albert ARIBAUD wrote:
Hi Tom,
On Tue, 4 Feb 2014 12:05:33 -0500, Tom Rini trini@ti.com wrote:
When we tell the compiler to optimize for ARMv7 it assumes a default of unaligned accesses being supported at the hardware level and can make use of this to perform what it deems as an optimization in any case, including allowing for data to become unaligned. We explicitly disallow this hardware feature so we must tell the compiler.
Cc: Albert ARIBAUD albert.u.boot@aribaud.net Cc: Mans Rullgard mans@mansr.com Signed-off-by: Tom Rini trini@ti.com
NAK -- the discrepancy between the compiler being told to allow native unaligned accesses while at the same time telling the hardware to trap them is conscious and voluntary. It was chosen to help detect unaligned accesses which are rarely necessary and can be explicitly performed by software on a case by case basis.
If and when a specific file requires unaligned access which cannot be made by some other mean than enabling -mno-unaligned-access, then this file should have it added, not the whole of U-Boot.
Right, I recall the discussion, and we chose wrong.
I am quite prepared to discuss whether we chose wrong or right, and to change my mind when the conditions are right, but I'll need more than such a short and simple statement. :)
I already gave you a detailed explanation some months ago. You refused to read it.
I can hardly have "refused to read" a message which I *answered*, laid out how I thought the issue should be solved... and got no answer after this.
Now, are we going to discuss the technical issue or is this going to go debian-TC -- which I wouldn't see the point of.
Well, here's the point that I haven't seen an answer to. If we tell the compiler "you may choose to use unaligned accesses as an optimization, we support this", the compiler says "OK, I shall do that", and then we fail at run time because we don't actually allow the unaligned access, how is this not a problem on our end for the first part of the equation, keeping in mind that the real world is poorly designed and when we write code to this reality the compiler does the correct thing in all cases (or it's a compiler bug).