linux-kernel - Re: [PATCH v4 11/23] powerpc/syscall: Rename syscall

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Date:   Tue, 2 Feb 2021 07:15:24 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Nicholas Piggin <npiggin@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        David Laight <David.Laight@...LAB.COM>,
        Michael Ellerman <mpe@...erman.id.au>,
        "msuchanek@...e.de" <msuchanek@...e.de>,
        Paul Mackerras <paulus@...ba.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v4 11/23] powerpc/syscall: Rename syscall_64.c into
 syscall.c



Le 28/01/2021 à 00:50, Nicholas Piggin a écrit :
> Excerpts from David Laight's message of January 26, 2021 8:28 pm:
>> From: Nicholas Piggin
>>> Sent: 26 January 2021 10:21
>>>
>>> Excerpts from Christophe Leroy's message of January 26, 2021 12:48 am:
>>>> syscall_64.c will be reused almost as is for PPC32.
>>>>
>>>> Rename it syscall.c
>>>
>>> Could you rename it to interrupt.c instead? A system call is an
>>> interrupt, and the file now also has code to return from other
>>> interrupts as well, and it matches the new asm/interrupt.h from
>>> the interrupts series.
>>
>> Hmmm....
>>
>> That might make it harder for someone looking for the system call
>> entry code to find it.
> 
> It's very grep'able.
> 
>> In some sense interrupts are the simpler case.
>>
>> Especially when comparing with other architectures which have
>> special instructions for syscall entry.
> 
> powerpc does have a special instruction for syscall, and it causes a
> system call interrupt.
> 
> I'm not sure about other architectures, but for powerpc its more
> sensible to call it interrupt.c than syscall.c.

Many other architectures have a syscall.c but for a different purpose: it contains arch specific 
system calls. We have that in powerpc as well, it is called syscalls.c

So to avoid confusion, I'll rename it. But I think "interrupt" is maybe not the right name. An 
interrupt most of the time refers to IRQ. For me system call is not an interrupt in the way it 
doesn't unexpectedly interrupt a program flow. In powerpc manuals it is generally called exceptions, 
no I'm more inclined to call it exception.c

Christophe