From: Segher Boessenkool <segher@kernel.crashing.org>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: ravi.bangoria@linux.ibm.com, ananth@linux.ibm.com,
jniethe5@gmail.com, paulus@samba.org,
Sandipan Das <sandipan@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, dja@axtens.net
Subject: Re: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation
Date: Mon, 1 Mar 2021 20:37:33 -0600 [thread overview]
Message-ID: <20210302023732.GH29191@gate.crashing.org> (raw)
In-Reply-To: <20210204082753.GI210@DESKTOP-TDPLP67.localdomain>
Hi!
I didn't see this until now, almost a month later, sorry about that :-)
On Thu, Feb 04, 2021 at 01:57:53PM +0530, Naveen N. Rao wrote:
> On 2021/02/03 03:17PM, Segher Boessenkool wrote:
> > Power8 does:
> >
> > Load with Update Instructions (RA = 0)
> > EA is placed into R0.
> > Load with Update Instructions (RA = RT)
> > EA is placed into RT. The storage operand addressed by EA is
> > accessed, but the data returned by the load is discarded.
>
> I'm actually not seeing that. This is what I am testing with:
> li 8,0xaaa
> mr 6,1
> std 8,64(6)
> #ldu 6,64(6)
> .long 0xe8c60041
>
> And, r6 always ends up with 0xaea. It changes with the value I put into
> r6 though.
That is exactly the behaviour specified for p8. 0aaa+0040=0aea.
> Granted, this is all up in the air, but it does look like there is more
> going on and the value isn't the EA or the value at the address.
That *is* the EA. The EA is the address the insn does the access at.
Segher
next prev parent reply other threads:[~2021-03-02 2:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 6:38 [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation Sandipan Das
2021-02-03 6:38 ` [PATCH v2 2/3] powerpc: sstep: Fix store " Sandipan Das
2021-02-03 6:38 ` [PATCH v2 3/3] powerpc: sstep: Fix darn emulation Sandipan Das
2021-02-03 9:49 ` [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation Naveen N. Rao
2021-02-03 10:35 ` Sandipan Das
2021-02-03 11:37 ` Sandipan Das
2021-02-04 0:53 ` Michael Ellerman
2021-02-03 21:17 ` Segher Boessenkool
2021-02-04 8:27 ` Naveen N. Rao
2021-03-02 2:37 ` Segher Boessenkool [this message]
2021-03-03 16:31 ` Naveen N. Rao
2021-03-04 15:45 ` Segher Boessenkool
2021-03-04 1:06 ` Naveen N. Rao
2021-02-04 10:29 ` David Laight
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