From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Jaxson Han <jaxson.han@arm.com>,
linux-arm-kernel@lists.infradead.org,
Robin Murphy <Robin.Murphy@arm.com>
Subject: Re: [PATCH v3] Makefile: Tell compiler to generate bare-metal code
Date: Mon, 17 Jan 2022 18:04:54 +0000 [thread overview]
Message-ID: <YeWvxtoZqpTNCOhb@shell.armlinux.org.uk> (raw)
In-Reply-To: <YeWsN+/IFkOJCK/S@shell.armlinux.org.uk>
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@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.
Oh, this is not the kernel. Please make it clear as you're posting to
the linux-arm-kernel mailing list...
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2022-01-17 18:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-17 15:33 [PATCH v3] Makefile: Tell compiler to generate bare-metal code Andre Przywara
2022-01-17 16:47 ` Mark Rutland
2022-01-17 16:53 ` Andre Przywara
2022-01-17 17:24 ` Mark Rutland
2022-01-17 17:49 ` Russell King (Oracle)
2022-01-17 18:04 ` Russell King (Oracle) [this message]
2022-01-17 18:25 ` Andre Przywara
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