Re: [edk2-devel] [PATCH] CryptoPkg/FltUsedLib: Add FltUsedLib for float.

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

On Mon, 30 Mar 2020 at 23:29, Matthew Carlson via Groups.Io
<macarl=microsoft.com@groups.io> wrote:
>
> So it's not required by OpenSSL, it's required by the compiler whenever floating point is used, which can be in multiple places. For example, this is used in mu_plus (the Microsoft UEFI value add to EDK2) by the OnScreenKeyboard driver as well as the UiToolKit driver. If you happen to use BaseCryptLib or the intrinsic in a driver that happens to need crypto as well, it can break due to multiple.
>
> I do agree, this only applies to MSVC and requiring every platform to add a line in their DSC would be a situation I would prefer to avoid if possible. Is there a way to specify a library dependency only if a toolchain is being used?

Yes, so this either belongs in one of the IntrinsicsLibs we have, or
in the various Entrypoint libraries we have for PEIMs, DXEs, etc.

However, given that we are talking about static libraries here, adding
a source file that *only* defines __fltused (and nothing else) to any
library should also work, as the resulting object file will only be
incorporated by the linker if it is needed to satisfy a symbol
dependency, and so it can never cause a conflict if it is the only
symbol in the object.