[PATCH v1 1/2] RISC-V: move zicsr/zifencei spec version check to Kconfig

[Conor Dooley]

On Mon, Mar 06, 2023 at 03:52:27PM -0800, Palmer Dabbelt wrote:
> On Fri, 24 Feb 2023 09:00:09 PST (-0800), Conor Dooley wrote:
> > On Fri, Feb 24, 2023 at 09:37:28AM -0700, Nathan Chancellor wrote:
> > > On Thu, Feb 23, 2023 at 10:05:45PM +0000, Conor Dooley wrote:
> > 
> > > > ---
> > > >  arch/riscv/Kconfig  | 10 ++++++++++
> > > >  arch/riscv/Makefile |  5 +----
> > > >  2 files changed, 11 insertions(+), 4 deletions(-)
> > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > > > index cebf0c5f8824..4eb0ef8314b3 100644
> > > > --- a/arch/riscv/Kconfig
> > > > +++ b/arch/riscv/Kconfig
> > > > @@ -288,6 +288,16 @@ config ARCH_RV64I
> > > >  >  endchoice
> > > >  > +config TOOLCHAIN_NEEDS_SPEC_20191213
> > > 
> > > This symbol's name is a little confusing to me, how does the toolchain
> > > need spec version 20191213. Maybe 'SPEC_20191213' should be something
> > > like 'EXPLICIT_ZICSR_ZIFENCEI'? Otherwise, maybe it should be something
> > > like 'TOOLCHAIN_HAS_DEFAULT_SPEC_20191213'? Sorry for the bikeshed but I
> > > think most Kconfig symbols should be self describing.
> > 
> > Yah I can do that. I actually had this as the DEFAULT_SPEC variant
> > before and changed it - I'll switch it to the EXPLICIT one.
> > Thanks for taking a look Nathan :)
> 
> Another option here would be to use the `-misa-spec` argument for GCC, to
> make it match LLVM's spec version.

I'm not entirely sure what you're getting at.
You're the toolchain guy, but my understanding was that gas and gcc have
that option, but not ld, which rules out my initial interpretation. 
Are you suggesting that we always pass -misa-spec=<pre-zicsr_zifencei> to
gcc so that we are using the same misa-spec for both gnu and llvm
toolchain bits?

My instinctive thought was that that is kinda fragile to things
misaligning between gcc/llvm, but given I seem to end up looking at this
every month, we're really fragile to changes in either camp anyway...

I can go spin an alternative v2 of this up if I have understood you
correctly.

Thanks,
Conor.
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