From: Andreas Larsson <andreas@gaisler.com>
To: David Miller <davem@davemloft.net>, triegel@redhat.com
Cc: libc-alpha@sourceware.org, adhemerval.zanella@linaro.org,
carlos@redhat.com, software@gaisler.com
Subject: Re: [RFC][PATCH 0/2] Make sparcv8 work again on cas enabled hardware
Date: Fri, 04 Nov 2016 10:28:00 -0000 [thread overview]
Message-ID: <581C62A2.8050204@gaisler.com> (raw)
In-Reply-To: <20161103.132213.598669006383889263.davem@davemloft.net>
On 2016-11-03 18:22, David Miller wrote:
> From: Torvald Riegel <triegel@redhat.com>
> Date: Thu, 03 Nov 2016 16:39:21 +0100
>
>> Is there any difference between the additional CAS on a v8 and the CAS
>> on a v9? If there should be none (eg, same instruciton encoding etc.),
>> we wouldn't need a runtime check for this, would we?
>
> A quick look at binutils shows that the encoding appears to be the same.
The general encoding of the CASA instruction is the same, but on sparcv9
the ASI to use is the primary address space ASI 0x80 and on LEON the ASI
to use is the user data space ASI 0xa. So different instruction
encodings needs to be used.
Unfortunately there is no way general way short of trying to use the
CASA instruction and taking a care of a possible illegal instruction to
detect if a LEON3 system has CAS or not. But CAS support is implied by
the the -mcpu=leon3 flag, and LEON3 systems without CAS can use -mcpu=v8.
--
Best regards,
Andreas Larson
next prev parent reply other threads:[~2016-11-04 10:28 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 15:08 Andreas Larsson
2016-11-01 15:08 ` [RFC][PATCH 2/2] sparc32: Use cas for atomic_* operations and use general pthread_barrier_wait Andreas Larsson
2016-11-04 18:37 ` David Miller
2016-11-04 18:44 ` David Miller
2016-11-01 15:08 ` [RFC][PATCH 1/2] sparc32: Mark sendmsg and recvmsg system calls as unsupported Andreas Larsson
2016-11-01 17:28 ` Adhemerval Zanella
2016-11-02 11:38 ` Andreas Larsson
2016-11-02 12:49 ` Adhemerval Zanella
2016-11-04 18:36 ` David Miller
2016-11-01 16:00 ` [RFC][PATCH 0/2] Make sparcv8 work again on cas enabled hardware Torvald Riegel
2016-11-01 16:09 ` David Miller
2016-11-01 16:46 ` Torvald Riegel
2016-11-01 16:51 ` David Miller
2016-11-02 10:05 ` Torvald Riegel
2016-11-02 11:29 ` Andreas Larsson
2016-11-02 15:32 ` David Miller
2016-11-02 22:33 ` Torvald Riegel
2016-11-03 2:52 ` David Miller
2016-11-03 15:39 ` Torvald Riegel
2016-11-03 17:22 ` David Miller
2016-11-03 18:41 ` Adhemerval Zanella
2016-11-03 20:33 ` David Miller
2016-11-03 21:29 ` Adhemerval Zanella
2016-11-03 22:25 ` Torvald Riegel
2016-11-04 10:28 ` Andreas Larsson [this message]
2016-11-04 15:23 ` David Miller
2016-11-04 13:55 ` Richard Henderson
2016-11-04 15:31 ` David Miller
2016-11-04 16:10 ` Richard Henderson
2016-11-04 14:04 ` Richard Henderson
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