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From: Alistair Popple <alistair@popple.id.au>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Jordan Niethe <jniethe5@gmail.com>,
	Daniel Axtens <dja@axtens.net>,
	linuxppc-dev@lists.ozlabs.org,
	Balamuruhan S <bala24@linux.ibm.com>
Subject: Re: [PATCH v3 01/14] powerpc: Enable Prefixed Instructions
Date: Wed, 04 Mar 2020 10:20:23 +1100	[thread overview]
Message-ID: <3079586.NPOWFCaNNt@townsend> (raw)
In-Reply-To: <1582864874.q013n2u3v1.astroid@bobo.none>

> But hmm, the dt_cpu_ftrs parsing should be picking those up and setting
> them by default I would think (or maybe not because you don't expect
> FSCR bit if OS support is not required).

Right - the generic dt_cpu_ftrs didn't do the FSCR enablement which I assume 
is because if OS support is required anyway we can just add it in a similar 
way to the below patch. My thinking was that we could use it to disable prefix 
with a firmware if required, however outside of a lab environment there isn't 
much practical use for that so I'm ok with just doing something similar to the 
below.

> All the other FSCR bits are done similarly to this AFAIKS:
> 
>  https://patchwork.ozlabs.org/patch/1244476/
> 
> I would do that for now rather than digging into it too far, but we
> should look at cleaning that up and doing something more like what
> you have here.
>
> >> >  struct dt_cpu_feature_match {
> >> >  
> >> >       const char *name;
> >> >       int (*enable)(struct dt_cpu_feature *f);
> >> > 
> >> > @@ -626,6 +648,7 @@ static struct dt_cpu_feature_match __initdata
> >> > 
> >> >       {"vector-binary128", feat_enable, 0},
> >> >       {"vector-binary16", feat_enable, 0},
> >> >       {"wait-v3", feat_enable, 0},
> >> > 
> >> > +     {"prefix-instructions", feat_enable_prefix, 0},
> >> 
> >> That's reasonable to make that a feature, will it specify a minimum
> >> base set of prefix instructions or just that prefix instructions
> >> with the prefix/suffix arrangement exist?
> > 
> > This was just going to be that they exist.
> > 
> >> You may not need "-instructions" on the end, none of the other
> >> instructions do.
> > 
> > Good point.
> > 
> >> I would maybe just hold off upstreaming the dt_cpu_ftrs changes for
> >> a bit. We have to do a pass over new CPU feature device tree, and
> >> some compatibility questions have come up recently.
> >> 
> >> If you wouldn't mind just adding the new [H]FSCR bits and faults
> >> upstream for now, that would be good.
> > 
> > No problem.
> 
> Thanks,
> Nick





  reply	other threads:[~2020-03-03 23:22 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-26  4:07 [PATCH v3 00/14] Initial Prefixed Instruction support Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 01/14] powerpc: Enable Prefixed Instructions Jordan Niethe
2020-02-26  6:46   ` Nicholas Piggin
2020-02-28  2:52     ` Jordan Niethe
2020-02-28  4:48       ` Nicholas Piggin
2020-03-03 23:20         ` Alistair Popple [this message]
2020-02-26  4:07 ` [PATCH v3 02/14] powerpc: Define new SRR1 bits for a future ISA version Jordan Niethe
2020-03-03 23:31   ` Alistair Popple
2020-02-26  4:07 ` [PATCH v3 03/14] powerpc sstep: Prepare to support prefixed instructions Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 04/14] powerpc sstep: Add support for prefixed load/stores Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 05/14] powerpc sstep: Add support for prefixed fixed-point arithmetic Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 06/14] powerpc: Support prefixed instructions in alignment handler Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 07/14] powerpc/traps: Check for prefixed instructions in facility_unavailable_exception() Jordan Niethe
2020-02-26  6:49   ` Nicholas Piggin
2020-02-26 23:52     ` Jordan Niethe
2020-02-28  1:57       ` Nicholas Piggin
2020-02-26  4:07 ` [PATCH v3 08/14] powerpc/xmon: Remove store_inst() for patch_instruction() Jordan Niethe
2020-02-26  7:00   ` Nicholas Piggin
2020-02-26 23:54     ` Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 09/14] powerpc/xmon: Add initial support for prefixed instructions Jordan Niethe
2020-02-26  7:06   ` Nicholas Piggin
2020-02-27  0:11     ` Jordan Niethe
2020-02-27  7:14       ` Christophe Leroy
2020-02-28  0:37         ` Jordan Niethe
2020-02-28  1:23           ` Nicholas Piggin
2020-02-26  4:07 ` [PATCH v3 10/14] powerpc/xmon: Dump " Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 11/14] powerpc/kprobes: Support kprobes on " Jordan Niethe
2020-02-26  7:14   ` Nicholas Piggin
2020-02-27  0:58     ` Jordan Niethe
2020-02-28  1:47       ` Nicholas Piggin
2020-02-28  1:56         ` Nicholas Piggin
2020-02-28  3:23         ` Jordan Niethe
2020-02-28  4:53           ` Nicholas Piggin
2020-02-26  4:07 ` [PATCH v3 12/14] powerpc/uprobes: Add support for " Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 13/14] powerpc/hw_breakpoints: Initial " Jordan Niethe
2020-02-26  4:07 ` [PATCH v3 14/14] powerpc: Add prefix support to mce_find_instr_ea_and_pfn() Jordan Niethe

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