linux-kernel - Re: [net-next PATCH] net: phy: aquantia: drop wrong endianness conversion for addr and CRC

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Date:   Wed, 22 Nov 2023 19:39:44 +0100
From:   Christian Marangi <ansuelsmth@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     "Russell King (Oracle)" <linux@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Robert Marko <robimarko@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [net-next PATCH] net: phy: aquantia: drop wrong endianness
 conversion for addr and CRC

On Wed, Nov 22, 2023 at 10:23:47AM -0800, Jakub Kicinski wrote:
> On Wed, 22 Nov 2023 18:53:39 +0100 Christian Marangi wrote:
> > So they DO get converted to the HOST endian on reading the firmware from
> > an nvmem cell or a filesystem?
> 
> They don't get converted when "reading from nvmem / fs". 
> They get converted when you do:
> 
> 		word = get_unaligned((const u32 *)(data + pos));
> 
> get_unaligned() is basically:
> 
> #if BIGENDIAN
> #define		get_unaligned	get_unaligned_be32
> #else
> #define		get_unaligned	get_unaligned_le32
> #endif
> 
> so you'll get different behavior here depending on the CPU.

Ugh... If that is true this is bad...

When get_unaligned was suggested, I checked if the thing was doing any
kind of conversion and from [1] I tought it was just getting the
pointer.

I can't find the entry where the thing is done. Is this some kind of
include magic with asm specific API?

[1] https://elixir.bootlin.com/linux/latest/source/include/asm-generic/unaligned.h#L22

-- 
	Ansuel