On Thu, 24 Mar 2016, Tom Rini wrote:
On Thu, Mar 24, 2016 at 08:50:03AM +0100, Albert ARIBAUD wrote:
Hello Tom,
On Wed, 23 Mar 2016 17:36:17 -0400, Tom Rini <tr...@konsulko.com> wrote:
On Wed, Mar 23, 2016 at 06:08:45PM +0100, Albert ARIBAUD wrote:
Hello Tom,
On Wed, 23 Mar 2016 09:22:38 -0400, Tom Rini <tr...@konsulko.com> wrote:
On Wed, Mar 23, 2016 at 01:53:35PM +0100, Albert ARIBAUD wrote:
Hello Marek,
On Sun, 20 Mar 2016 17:15:34 +0100, Marek Vasut <ma...@denx.de> wrote:
This patch decouples U-Boot binary from the toolchain on systems where
private libgcc is available. Instead of pulling in functions provided
by the libgcc from the toolchain, U-Boot will use it's own set of libgcc
functions. These functions are usually imported from Linux kernel, which
also uses it's own libgcc functions instead of the ones provided by the
toolchain.
This patch solves a rather common problem. The toolchain can usually
generate code for many variants of target architecture and often even
different endianness. The libgcc on the other hand is usually compiled
for one particular configuration and the functions provided by it may
or may not be suited for use in U-Boot. This can manifest in two ways,
either the U-Boot fails to compile altogether and linker will complain
or, in the much worse case, the resulting U-Boot will build, but will
misbehave in very subtle and hard to debug ways.
I don't think using private libgcc by default is a good idea.
U-Boot's private libgcc is not a feature of U-Boot, but a fix for some
cases where a target cannot properly link with the libgcc provided by
the (specific release of the) GCC toolchain in use. Using private libgcc
to other cases than these does not fix or improve anything; those
other cases were working and did not require any fix in this respect.
This isn't true, exactly. If using clang for example everyone needs to
enable this code. We're also using -fno-builtin -ffreestanding which
should limit the amount of interference from the toolchain. And we get
that.
You mean clang does not produce self-sustained binaries?
clang does not provide "libgcc", so there's no -lgcc providing all of
the functions that are (today) in:
_ashldi3.S _ashrdi3.S _divsi3.S _lshrdi3.S _modsi3.S _udivsi3.S
_umodsi3.S div0.S _uldivmod.S
which aside from __modsi3 and __umodsi3 are all __aeabi_xxx
(ok, that explains what you mean by AEABI functions -- those are
actually not functions defined by the AEABI, but functions that the GCC
folks prefixed with __aeabi.)
No. For reference,
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0043d/IHI0043D_rtabi.pdf
and chapter 4 is all about the support library. We are entirely in our
right to do either of (a) use the compiler-provided library (b) provide
our own implementation of what we need. The kernel opts for (b) and I
would like us to follow that as well, consistently, rather than ad-hoc.
Second that. By having _EVERYTHING_ coming from U-Boot we are taking care of
_ANY_ possible mismatch between what we are building and pre-built toolchain
libraries. Soft float in ARM U-Boot and VFP hard float in most i.MX6/7
toolchains is just one of such prominent examples.
U-Boot is a standalone program not supposed to coexist with any external
applications i.e. it is totally self-sufficient, not living in some kind of
system environment so it makes perfect sense for it not to use _ANY_
external parts in the final binary.
---
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