linux-kernel - Re: [PATCH 2/2] Propeller: Remove the architecture specific config

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Message-ID: <CALJ9ZPM9pUw=M4fFLKRTyr0k4T8Y=4DY+ob96UW_-dWZRTeurA@mail.gmail.com>
Date: Fri, 31 Jan 2025 14:36:13 -0800
From: Yabin Cui <yabinc@...gle.com>
To: Rong Xu <xur@...gle.com>
Cc: Nathan Chancellor <nathan@...nel.org>, Masahiro Yamada <masahiroy@...nel.org>, 
	Will Deacon <will@...nel.org>, Han Shen <shenhan@...gle.com>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, Kees Cook <kees@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Sami Tolvanen <samitolvanen@...gle.com>, 
	Alice Ryhl <aliceryhl@...gle.com>, "Mike Rapoport (Microsoft)" <rppt@...nel.org>, 
	Samuel Holland <samuel.holland@...ive.com>, "Paul E. McKenney" <paulmck@...nel.org>, 
	Arnd Bergmann <arnd@...db.de>, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] Propeller: Remove the architecture specific config

Tested-by: Yabin Cui <yabinc@...gle.com>

On Wed, Dec 11, 2024 at 11:48 PM Rong Xu <xur@...gle.com> wrote:
>
>  (o
>
> On Wed, Dec 11, 2024 at 3:06 PM Nathan Chancellor <nathan@...nel.org> wrote:
> >
> > Hi Rong,
> >
> > On Wed, Dec 11, 2024 at 02:29:43PM -0800, Rong Xu wrote:
> > > The CONFIG_PROPELLER_CLANG option currently depends on
> > > ARCH_SUPPORTS_PROPELLER_CLANG, but this dependency seems unnecessary.
> > >
> > > Remove ARCH_SUPPORTS_PROPELLER_CLANG and allow users to control
> > > Propeller builds solely through CONFIG_PROPELLER_CLANG. This simplifies
> > > the kconfig and avoids potential confusion.
> > >
> > > Signed-off-by: Rong Xu <xur@...gle.com>
> > > Suggested-by: Will Deacon <will@...nel.org>
> >
> > In commit d5dc95836147 ("kbuild: Add Propeller configuration for kernel
> > build"), you added .llvm_bb_addr_map to arch/x86/kernel/vmlinux.lds.S.
> > Was this to address a orphan section warning from the linker? Is that
> > same change needed in the linker scripts of the other architectures that
> > clang supports building in the kernel?
>
> The .llvm_bb_addr_map section is created when compiling with the
> -fbasic-block-address-map flag (or the older -fbasic-block-sections=labels
> option), with LLVM. We need the change in the linker script to group the
> sections together and emit in the final vmlinux.
>
> This applies to all architectures, as LLVM can generate these sections for
> any architecture when the corresponding option is used.
>
> The statement that AutoFDO and Propeller are only supported on certain
> platforms really refers to the availability of *native* profile generation:
> the native profile generation is only available on these platforms.
>
> Hope this helps,
>
> -Rong
>
> > Cheers,
> > Nathan
> >
> > > ---
> > >  arch/Kconfig     | 4 ----
> > >  arch/x86/Kconfig | 1 -
> > >  2 files changed, 5 deletions(-)
> > >
> > > diff --git a/arch/Kconfig b/arch/Kconfig
> > > index 0b36d74d47031..83731b858ba65 100644
> > > --- a/arch/Kconfig
> > > +++ b/arch/Kconfig
> > > @@ -828,12 +828,8 @@ config AUTOFDO_CLANG
> > >
> > >         If unsure, say N.
> > >
> > > -config ARCH_SUPPORTS_PROPELLER_CLANG
> > > -     bool
> > > -
> > >  config PROPELLER_CLANG
> > >       bool "Enable Clang's Propeller build"
> > > -     depends on ARCH_SUPPORTS_PROPELLER_CLANG
> > >       depends on CC_IS_CLANG && CLANG_VERSION >= 190000
> > >       help
> > >         This option enables Clang’s Propeller build. When the Propeller
> > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > > index 9363d9cc9a00a..6c633d93c6390 100644
> > > --- a/arch/x86/Kconfig
> > > +++ b/arch/x86/Kconfig
> > > @@ -128,7 +128,6 @@ config X86
> > >       select ARCH_SUPPORTS_LTO_CLANG
> > >       select ARCH_SUPPORTS_LTO_CLANG_THIN
> > >       select ARCH_SUPPORTS_RT
> > > -     select ARCH_SUPPORTS_PROPELLER_CLANG    if X86_64
> > >       select ARCH_USE_BUILTIN_BSWAP
> > >       select ARCH_USE_CMPXCHG_LOCKREF         if X86_CMPXCHG64
> > >       select ARCH_USE_MEMTEST
> > > --
> > > 2.47.0.338.g60cca15819-goog
> > >