[U-Boot] [PATCH] ARM: Add comments why -msoft-float is used.

Wolfgang Denk wd at denx.de
Sun Feb 20 09:42:42 CET 2011


Dear Alexander Holler,

In message <1298171532-5296-1-git-send-email-holler at ahsoftware.de> you wrote:
> Without -msoft-float the compiler would be allowed to use certain
> floating-point instructions (VFP/NEON) e.g. for optimizations, which
> would require additional code, for example to save contexts for
> interrupts. Add a comment which describes this in short words.

Hm... why do you see a need to explain this for ARM, but not so for
the other architectrures, say for PowerPC?

If you really want to add this, then it should probably be somewhere
in the REAME or another central place of documentation (instead of
distributed over tons of Makefiles), and to make your message
understood you might want to add "additional code" may mean that
additional function blocks in the respective SoC may need to be
initialized and, for example, clocked, which may for example
significantly increase the power dissipation of the system.

> +# -msoft-float forces the compiler to not use any fp-related instructions.

Well, now this is a commonplace that says about nothing and can be
leftout as well.

Best regards,

Wolfgang Denk

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