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

[Nadav Amit]

From: Logan Gunthorpe
Sent: November 8, 2018 at 8:00:33 PM GMT
> To: Nadav Amit <namit@xxxxxxxxxx>, hpa@xxxxxxxxx <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>, X86 ML <x86@xxxxxxxxxx>, Sam Ravnborg <sam@xxxxxxxxxxxx>, Michal Marek <michal.lkml@xxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Linux Kbuild mailing list <linux-kbuild@xxxxxxxxxxxxxxx>, Stephen Bates <sbates@xxxxxxxxxxxx>
> 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 donât 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 donât
>> 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.