[PATCH v3] Makefile: Tell compiler to generate bare-metal code

[Russell King (Oracle)]

On Mon, Jan 17, 2022 at 05:49:43PM +0000, Russell King (Oracle) wrote:
> On Mon, Jan 17, 2022 at 03:33:48PM +0000, Andre Przywara wrote:
> > Our GCC invocation does not provide many parameters, which lets the
> > toolchain fill in its own default setup.
> > In case of a native build or when using a full-featured cross-compiler,
> > this probably means Linux userland, which is not what we want for a
> > bare-metal application like boot-wrapper.
> > 
> > Tell the compiler to forget about those standard settings, and only use
> > what we explicitly ask for. In particular that means to not use toolchain
> > provided libraries, since they might pull in more code than we want, and
> > might not run well in the boot-wrapper environment.
> > 
> > Disable the stack protector, as this adds code that relies on userland:
> > "If a guard check fails, an error message is printed and the program
> > exits." (from the gcc manpage).
> > 
> > Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> > ---
> > Hi,
> > 
> > compared to [PATCH v2 3/9] this drops the more contentious options (for
> > now, at least), and focuses on what's really needed. Including
> > -fno-stack-protector, as the need for this showed up in the cleanup series
> > already.
> 
> There is history here. -ffreestanding has been tried before. See:
> 
> https://patchwork.kernel.org/project/linux-kbuild/patch/20200817220212.338670-5-ndesaulniers@google.com/
> 
> Have the issues in that thread been addressed?
> 
> If not, -ffreestanding does not belong in the top-level makefile.

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