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From: Qais Yousef <qais.yousef@imgtec.com>
To: Paul Burton <paul.burton@imgtec.com>,
	David Daney <ddaney@caviumnetworks.com>,
	Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: David Daney <ddaney.cavm@gmail.com>, <linux-mips@linux-mips.org>,
	<ralf@linux-mips.org>, <Zubair.Kakakhel@imgtec.com>,
	<geert+renesas@glider.be>, <peterz@infradead.org>,
	<paul.gortmaker@windriver.com>, <macro@linux-mips.org>,
	<chenhc@lemote.com>, <cl@linux.com>, <mingo@kernel.org>,
	<richard@nod.at>, <zajec5@gmail.com>, <james.hogan@imgtec.com>,
	<keescook@chromium.org>, <tj@kernel.org>, <alex@alex-smith.me.uk>,
	<pbonzini@redhat.com>, <blogic@openwrt.org>,
	<linux-kernel@vger.kernel.org>, <markos.chandras@imgtec.com>,
	<dengcheng.zhu@imgtec.com>, <manuel.lauss@gmail.com>,
	<lars.persson@axis.com>, David Daney <david.daney@cavium.com>
Subject: Re: [PATCH 2/3] MIPS: Add full ISA emulator.
Date: Thu, 4 Dec 2014 10:45:30 +0000	[thread overview]
Message-ID: <54803B4A.10201@imgtec.com> (raw)
In-Reply-To: <20141204101229.GC5482@NP-P-BURTON>

By all means I don't really understand the whole issues surrounding this 
but this approach looks better to me as well. It seems more generic and 
future proof and at least I can understand the patch series.

But did I say I don't understand all of this? Would be nice to hear from 
more people :)

Qais

On 12/04/2014 10:16 AM, Paul Burton wrote:
> Nice work David, I like this approach. It's so much simpler than hacking
> atop the current dsemul code. I also imagine this could be reused for
> emulation of instructions removed in r6, when running pre-r6 userland
> binaries on r6 systems.
>
> On Wed, Dec 03, 2014 at 06:21:36PM -0800, David Daney wrote:
>> On 12/03/2014 05:56 PM, Leonid Yegoshin wrote:
>>> I see only two technical issues here which differs:
>>>
>>> 1.  You believe your GCC experts, I trust HW Architecture manual and
>>> don't trust toolchain people too much ==> we see a different value in
>>> fact that your approach has a subset of emulated ISAs (and it can't, of
>>> course, emulate anything because some custom opcodes are reused).
>> Yes, I agree that the emulation approach cannot handle some of the cases you
>> mention (most would have to be the result of hand coded assembly
>> specifically trying to break it).
> I'm not sure I'd agree even with that - ASEs & vendor-specific
> instructions could easily be added if necessary.
>
> On Thu, Dec 04, 2014 at 05:56:51PM -0800, Leonid Yehoshin wrote:
>>> 2.  My approach is ready to use and is used right now, you still have a
>>> framework which passed an initial boot.
> Subjective.
>
> Thanks,
>      Paul

WARNING: multiple messages have this Message-ID (diff)
From: Qais Yousef <qais.yousef@imgtec.com>
To: Paul Burton <paul.burton@imgtec.com>,
	David Daney <ddaney@caviumnetworks.com>,
	Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: David Daney <ddaney.cavm@gmail.com>,
	linux-mips@linux-mips.org, ralf@linux-mips.org,
	Zubair.Kakakhel@imgtec.com, geert+renesas@glider.be,
	peterz@infradead.org, paul.gortmaker@windriver.com,
	macro@linux-mips.org, chenhc@lemote.com, cl@linux.com,
	mingo@kernel.org, richard@nod.at, zajec5@gmail.com,
	james.hogan@imgtec.com, keescook@chromium.org, tj@kernel.org,
	alex@alex-smith.me.uk, pbonzini@redhat.com, blogic@openwrt.org,
	linux-kernel@vger.kernel.org, markos.chandras@imgtec.com,
	dengcheng.zhu@imgtec.com, manuel.lauss@gmail.com,
	lars.persson@axis.com, David Daney <david.daney@cavium.com>
Subject: Re: [PATCH 2/3] MIPS: Add full ISA emulator.
Date: Thu, 4 Dec 2014 10:45:30 +0000	[thread overview]
Message-ID: <54803B4A.10201@imgtec.com> (raw)
Message-ID: <20141204104530.qbGKU4D2G2n24Ly2DogwxvCN_Nb0-nXyqyRv5bcF_b8@z> (raw)
In-Reply-To: <20141204101229.GC5482@NP-P-BURTON>

By all means I don't really understand the whole issues surrounding this 
but this approach looks better to me as well. It seems more generic and 
future proof and at least I can understand the patch series.

But did I say I don't understand all of this? Would be nice to hear from 
more people :)

Qais

On 12/04/2014 10:16 AM, Paul Burton wrote:
> Nice work David, I like this approach. It's so much simpler than hacking
> atop the current dsemul code. I also imagine this could be reused for
> emulation of instructions removed in r6, when running pre-r6 userland
> binaries on r6 systems.
>
> On Wed, Dec 03, 2014 at 06:21:36PM -0800, David Daney wrote:
>> On 12/03/2014 05:56 PM, Leonid Yegoshin wrote:
>>> I see only two technical issues here which differs:
>>>
>>> 1.  You believe your GCC experts, I trust HW Architecture manual and
>>> don't trust toolchain people too much ==> we see a different value in
>>> fact that your approach has a subset of emulated ISAs (and it can't, of
>>> course, emulate anything because some custom opcodes are reused).
>> Yes, I agree that the emulation approach cannot handle some of the cases you
>> mention (most would have to be the result of hand coded assembly
>> specifically trying to break it).
> I'm not sure I'd agree even with that - ASEs & vendor-specific
> instructions could easily be added if necessary.
>
> On Thu, Dec 04, 2014 at 05:56:51PM -0800, Leonid Yehoshin wrote:
>>> 2.  My approach is ready to use and is used right now, you still have a
>>> framework which passed an initial boot.
> Subjective.
>
> Thanks,
>      Paul

  reply	other threads:[~2014-12-04 10:45 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-03 23:44 [PATCH 0/3] MIPS: Get ready for non-executable stack David Daney
2014-12-03 23:44 ` [PATCH 1/3] MIPS: Add FPU emulator counter for non-FPU instructions emulated David Daney
2014-12-03 23:44 ` [PATCH 2/3] MIPS: Add full ISA emulator David Daney
2014-12-03 23:55   ` Leonid Yegoshin
2014-12-03 23:55     ` Leonid Yegoshin
2014-12-04  0:20     ` David Daney
2014-12-04  0:20       ` David Daney
2014-12-04  0:52       ` Leonid Yegoshin
2014-12-04  0:52         ` Leonid Yegoshin
2014-12-04  1:29         ` David Daney
2014-12-04  1:29           ` David Daney
     [not found]           ` <547FBF63.70802@imgtec.com>
2014-12-04  2:21             ` David Daney
2014-12-04  2:21               ` David Daney
2014-12-04 10:16               ` Paul Burton
2014-12-04 10:16                 ` Paul Burton
2014-12-04 10:45                 ` Qais Yousef [this message]
2014-12-04 10:45                   ` Qais Yousef
2014-12-04 11:49       ` Maciej W. Rozycki
2014-12-04 17:40         ` David Daney
2014-12-04 17:40           ` David Daney
2014-12-04 20:32           ` Maciej W. Rozycki
2014-12-03 23:44 ` [PATCH 3/3] MIPS: Use full instruction emulation for FPU emulator delay slot emulation David Daney

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