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Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R
From: |
Maciej W. Rozycki |
Subject: |
Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900 |
Date: |
Thu, 25 Oct 2018 18:38:03 +0100 (BST) |
User-agent: |
Alpine 2.21 (LFD 202 2017-01-01) |
Hi Fredrik,
> > NB all but pipeline 1 instructions of these are also implemented by other
> > members of the TXx9 family. They seem to be referred to as just "multiply
> > and multiply-add instructions" in the TX79 manual (cf Section B.3.1).
>
> Would
>
> ASE_TOSHIBA_MMI -- TX79 128-bit multimedia instructions
> ASE_TOSHIBA_MAC -- TXx9 multiply and multiply-add instructions (MADD etc.)
> ASE_TOSHIBA_MAC1 -- TX79 pipeline 1 variant of ASE_TOSHIBA_MAC
> ASE_TOSHIBA_FMA -- R5900 FPU extensions (MADD.s etc.)
>
> be acceptable for the currently known Toshiba extensions? (Please propose
> better names.) One complication is that it seems only 8 bits are available
> for all vendor ASEs, and Toshiba would then scoop up half of those.
I'm not sure if every single random vendor-specific instruction (or a
bunch of) deserves its own ASE designation, be it internal or externally
exposed. I think the MMI set being a substantial architectural feature
makes sense to be shown in /proc/cpuinfo (in Linux), but I don't think
there's much more about it. It's limited to 2 implementations only, so
internally I think it can well be handled with a macro or static inline
function (as appropriate) which boil down to (CPU_R5900 || CPU_TX79).
And if you run out of bits for ASEs regardless, then I suggest just to
expand the field in question. In QEMU you can rely on the presence of the
`uint64_t' data type, so with only 8 bits exhausted you're far from
getting into trouble.
Maciej
- [Qemu-devel] [PATCH v8 37/38] target/mips: Define the R5900 CPU, (continued)
- [Qemu-devel] [PATCH v8 37/38] target/mips: Define the R5900 CPU, Fredrik Noring, 2018/10/21
- [Qemu-devel] [PATCH v8 38/38] linux-user/mips: Recognise the R5900 CPU model, Fredrik Noring, 2018/10/21
- Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900, Aleksandar Markovic, 2018/10/22
- Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900, Fredrik Noring, 2018/10/23
- Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900,
Maciej W. Rozycki <=
- Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900, Fredrik Noring, 2018/10/26
Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900, Philippe Mathieu-Daudé, 2018/10/22
Re: [Qemu-devel] [PATCH v8 00/38] target/mips: Limited support for the R5900, Fredrik Noring, 2018/10/23