Re: Toolchain question

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 9 August 2016 at 12:02, Leif Lindholm <leif.lindholm@linaro.org> wrote:
> On Tue, Aug 09, 2016 at 11:02:55AM +0200, Michael Zimmermann wrote:
>> > I use both, and never notice any difference. The primary differences
>> > are newlib vs glibc, and in some cases, whether symbols are decorated
>> > with a leading _
>> > The actual code generation is more dependent on the default target
>> > (i.e., -march/-mthumb for ARM) than bare-metal/hosted.
>>
>> > I only ever use the native
>> > compiler under Linux, or one of the linaro "-linux-" flavours if
>> > cross-compiling.
>>
>> I think that works because edk2 excludes all toolchain libs with -nostdlib
>> and fno-builtin.
>> I know from other bootloader projects like LK(LittleKernel) which link
>> against libgcc that compiling with anything but bare-metal toolchains makes
>> the resulting binary un-bootable.
>
> Sure, but those are effectively bugs in the corresponding projects.
>
> If they require special options/libraries they should (where possible)
> manually configure this, or (where not) exit with an error.
>

The problem with libgcc on AArch64 is that it is usually compiled with
the small code model, requiring 4 KB section alignment (up until
recently at least), and without -mstrict-align. In general, projects
that contain C code that should be able to execute with the MMU off
should steer clear of toolchain supplied target libraries.

-- 
Ard.