From: gengdongjiu <gengdongjiu@huawei.com>
To: Dave Martin <Dave.Martin@arm.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>,
"guohanjun@huawei.com" <guohanjun@huawei.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
Suzuki Poulose <Suzuki.Poulose@arm.com>,
"Catalin Marinas" <Catalin.Marinas@arm.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"Will Deacon" <Will.Deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxarm@huawei.com" <linuxarm@huawei.com>,
"zhihui.gao@huawei.com" <zhihui.gao@huawei.com>,
"huangshaoyu@huawei.com" <huangshaoyu@huawei.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"arvind.yadav.cs@gmail.com" <arvind.yadav.cs@gmail.com>,
Robin Murphy <Robin.Murphy@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"zhanghaibin7@huawei.com" <zhanghaibin7@huawei.com>
Subject: Re: [RESEND PATCH] arm64: v8.4: Support for new floating point multiplication variant
Date: Tue, 12 Dec 2017 09:44:06 +0800 [thread overview]
Message-ID: <d39500ed-0d17-a8b2-b7e2-9e48b5d8d43a@huawei.com> (raw)
In-Reply-To: <20171211132914.GJ22781@e103592.cambridge.arm.com>
On 2017/12/11 21:29, Dave Martin wrote:
>> Thanks for the point out.
>> In fact, this feature only adds two instructions:
>> FP16 * FP16 + FP32
>> FP16 * FP16 - FP32
>>
>> The spec call this bit to ID_AA64ISAR0_EL1.FHM, I do not know why it
>> will call "FHM", I think call it "FMLXL" may be better, which can
>> stand for FMLAL/FMLSL instructions.
> Although "FHM" is cryptic, I think it makes sense to keep this as "FHM"
> to match the ISAR0 field name -- we've tended to follow this policy
> for other extension names unless there's a much better or more obvious
> name available
Agree with you, I also think the "FHM" is better.
>
> For "FMLXL", new instructions might be added in the future that match
> the same pattern, and then "FMLXL" could become ambiguous. So maybe
> this is not the best choice.
Ok.
>
>>> Maybe something like "widening half-precision floating-point multiply
>>> accumulate" is acceptable wording consistent with the existing
>>> architecture, but I just made that up, so it's not official ;)
>> how about something like "performing a multiplication of each FP16
>> element of one vector with the corresponding FP16 element of a second
>> vector, and to add or subtract this without an intermediate rounding
>> to the corresponding FP32 element in a third vector."?
> We could have that, I guess.
Ok, thanks!
>
>>>> instructions set. Let the userspace know about it via a
>>>> HWCAP bit and MRS emulation.
prev parent reply other threads:[~2017-12-12 1:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-09 15:28 [RESEND PATCH] arm64: v8.4: Support for new floating point multiplication variant Dongjiu Geng
2017-12-11 11:59 ` Dave P Martin
2017-12-11 12:47 ` gengdongjiu
2017-12-11 13:29 ` Dave Martin
2017-12-11 18:58 ` Suzuki K Poulose
2017-12-12 2:07 ` gengdongjiu
2017-12-12 1:44 ` gengdongjiu [this message]
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