Re: [PATCH 1/7] efi/riscv: libstub: mark when compiling libstub

[Conor Dooley <conor@kernel.org>]

On Sun, Nov 13, 2022 at 06:20:29PM +0100, Heiko Stübner wrote:
> Am Sonntag, 13. November 2022, 18:16:10 CET schrieb Conor Dooley:
> > On Thu, Nov 10, 2022 at 05:49:18PM +0100, Heiko Stuebner wrote:
> > > From: Heiko Stuebner <heiko.stuebner@vrull.eu>
> > > 
> > > We want to runtime-optimize some core functions (str*, mem*)
> > > but not have this leak into libstub. Instead libstub
> > > for the short while it's running should just use the generic
> > 
> > Totally pedantic reword, mostly b/c I am an eejit and confused myself
> > the first time reading this:
> > 
> > "Instead, libstub, for the short while it's running, should just use
> > the generic implementation."
> > 
> > > implementation.
> > > 
> > > To be able to determine whether functions are getting compiled
> > > as part of libstub or not, add a compile-flag we can check
> > > via #ifdef.
> > 
> > Exempting the stub makes sense to me given when it runs. What's the
> > actual downside of not exempting it though?
> 
> You run into build-errors.

Ah right, I figured it had to be something more than avoiding some
overhead. Might be worth noting that the purpose is to avoid build
errors.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

> 
> I.e. the alternatives (zbb-variants in this case) get compiled
> so there is the reference to the _strlen_zbb function in the efi-stub,
> which of course is not fullfillable, hence the "magic" in patch6 :-) .
> 
> 
> Heiko
> 
> 
> > > Signed-off-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
> > > ---
> > >  drivers/firmware/efi/libstub/Makefile | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> > > index b1601aad7e1a..39c8e3da1937 100644
> > > --- a/drivers/firmware/efi/libstub/Makefile
> > > +++ b/drivers/firmware/efi/libstub/Makefile
> > > @@ -25,7 +25,7 @@ cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > >  				   -fno-builtin -fpic \
> > >  				   $(call cc-option,-mno-single-pic-base)
> > >  cflags-$(CONFIG_RISCV)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > > -				   -fpic
> > > +				   -fpic -DRISCV_EFISTUB
> > >  cflags-$(CONFIG_LOONGARCH)	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
> > >  				   -fpie
> > >  
> > 
> 
> 
> 
> 
> 
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