linux-kernel - Re: [PATCH v9 02/10] Makefile: Prepare for using macros for inline asm

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Message-ID: <C0187502-9FC0-4FE2-BCD3-81B8B992F3A2@vmware.com>
Date:   Thu, 8 Nov 2018 20:18:25 +0000
From:   Nadav Amit <namit@...are.com>
To:     Logan Gunthorpe <logang@...tatee.com>,
        "hpa@...or.com" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
CC:     LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Stephen Bates <sbates@...thlin.com>
Subject: Re: [PATCH v9 02/10] Makefile: Prepare for using macros for inline
 asm

From: Logan Gunthorpe
Sent: November 8, 2018 at 8:00:33 PM GMT
> To: Nadav Amit <namit@...are.com>, hpa@...or.com <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
> Cc: LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>, Sam Ravnborg <sam@...nborg.org>, Michal Marek <michal.lkml@...kovi.net>, Thomas Gleixner <tglx@...utronix.de>, Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, Stephen Bates <sbates@...thlin.com>
> Subject: Re: [PATCH v9 02/10] Makefile: Prepare for using macros for inline asm
> 
> 
> 
> 
> On 2018-11-08 12:54 p.m., Nadav Amit wrote:
>> I don’t think the assembly stage needs to be done locally. gcc can still be
>> used to deploy the assembler. I am not too familiar with distcc, so I don’t
>> know whether the preprocessing supports multiple source-files, and whether
>> it has some strange-behavior when it comes to .S/.s files.
> 
> The problem is that it's the assembly stage that needs the extra
> macros.s and without that file being transferred somehow, that stage
> must be done locally.

I understand, but the idea is to have two stages, for instance:

  gcc ... -S -o .tmp_[unit].S [unit].c

and then

  gcc ... -D__ASSEMBLY__ arch/x86/kernel/macros.S .tmp_[unit].S

(Yes, I realize the .tmp_[unit].S was already preprocessed, but this way you
can combine both inputs)

Unfortunately, as I write this email (and run tests) I realize distcc is too
dumb to handle two input files:

  "(dcc_scan_args) do we have two inputs?  i give up "

Just great. So I guess macros.s would need to be concatenated with
.tmp_[unit].s as a separate (local) interim stage.