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Date: Mon, 3 Jun 2024 08:02:03 +0200
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Subject: Re: [PATCH 14/14] alpha: drop pre-EV56 support
To: Arnd Bergmann <arnd@kernel.org>, linux-alpha@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>,
 Richard Henderson <richard.henderson@linaro.org>,
 Ivan Kokshaysky <ink@jurassic.park.msu.ru>, Matt Turner
 <mattst88@gmail.com>, Alexander Viro <viro@zeniv.linux.org.uk>,
 Marc Zyngier <maz@kernel.org>, Linus Torvalds
 <torvalds@linux-foundation.org>, "Paul E. McKenney" <paulmck@kernel.org>,
 linux-kernel@vger.kernel.org, Greg KH <gregkh@linuxfoundation.org>
References: <20240503081125.67990-1-arnd@kernel.org>
 <20240503081125.67990-15-arnd@kernel.org>
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From: Jiri Slaby <jirislaby@kernel.org>
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Cc Greg for awareness too.

On 03. 05. 24, 10:11, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> All EV4 machines are already gone, and the remaining EV5 based machines
> all support the slightly more modern EV56 generation as well.
> Debian only supports EV56 and later.
> 
> Drop both of these and build kernels optimized for EV56 and higher
> when the "generic" options is selected, tuning for an out-of-order
> EV6 pipeline, same as Debian userspace.
> 
> Since this was the only supported architecture without 8-bit and
> 16-bit stores, common kernel code no longer has to worry about
> aligning struct members, and existing workarounds from the block
> and tty layers can be removed.

Yes!

For TTY pieces below:
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>

> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 2b2e6f0a54d6..2372f9357240 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -145,15 +145,12 @@ struct tty_operations;
>    * @count: count of open processes, reaching zero cancels all the work for
>    *	   this tty and drops a @kref too (but does not free this tty)
>    * @winsize: size of the terminal "window" (cf. @winsize_mutex)
> - * @flow: flow settings grouped together, see also @flow.unused
> + * @flow: flow settings grouped together
>    * @flow.lock: lock for @flow members
>    * @flow.stopped: tty stopped/started by stop_tty()/start_tty()
>    * @flow.tco_stopped: tty stopped/started by %TCOOFF/%TCOON ioctls (it has
>    *		      precedence over @flow.stopped)
> - * @flow.unused: alignment for Alpha, so that no members other than @flow.* are
> - *		 modified by the same 64b word store. The @flow's __aligned is
> - *		 there for the very same reason.
> - * @ctrl: control settings grouped together, see also @ctrl.unused
> + * @ctrl: control settings grouped together
>    * @ctrl.lock: lock for @ctrl members
>    * @ctrl.pgrp: process group of this tty (setpgrp(2))
>    * @ctrl.session: session of this tty (setsid(2)). Writes are protected by both
> @@ -161,7 +158,6 @@ struct tty_operations;
>    *		  them.
>    * @ctrl.pktstatus: packet mode status (bitwise OR of %TIOCPKT_ constants)
>    * @ctrl.packet: packet mode enabled
> - * @ctrl.unused: alignment for Alpha, see @flow.unused for explanation
>    * @hw_stopped: not controlled by the tty layer, under @driver's control for CTS
>    *		handling
>    * @receive_room: bytes permitted to feed to @ldisc without any being lost
> @@ -216,8 +212,7 @@ struct tty_struct {
>   		spinlock_t lock;
>   		bool stopped;
>   		bool tco_stopped;
> -		unsigned long unused[0];
> -	} __aligned(sizeof(unsigned long)) flow;
> +	} flow;
>   
>   	struct {
>   		struct pid *pgrp;
> @@ -225,8 +220,7 @@ struct tty_struct {
>   		spinlock_t lock;
>   		unsigned char pktstatus;
>   		bool packet;
> -		unsigned long unused[0];
> -	} __aligned(sizeof(unsigned long)) ctrl;
> +	} ctrl;
>   
>   	bool hw_stopped;
>   	bool closing;

-- 
js
suse labs