[linuxsh-dev] Re: [linux-sh:02783] Re: Where does __sdivsi3_i4 come from?

[Paul M. <le...@li...>]

On Thu, Jun 12, 2003 at 09:51:14AM +0900, kaz Kojima wrote:
> BTW, we don't have even local patches for -mno-implicit-fp against
> gcc-3.3 and gcc-3.4. I hear that the "stage1" of gcc-3.4 will end at
> July 4 and it means that we can't add any new features to the official
> gcc-3.4 after that day. I'm unsure that there are technical merits to
> use them when compiling kernel, but some folks would like to use a
> single (and new) SH gcc.
> Sugioka-san taught me that the option
>=20
>   -m4-nofpu -U__sh3__ -D__SH4__=3D1
>=20
> works for the kernel, at least to some extent. It slightly changes
> the ABI of function calling conventions even for the integer arguments,
> so we might need to check that it doesn't break something, though I
> guess there are few possibilities and we can easily fix them if any.
> So, it might be enough for the kernel and the kernel modules.
> # Caveat: Don't use -m4-nofpu for userland works without the complete
> #         understanding about this option.
>=20
> The third way might be to rewrite kernel so as to enable the use of FPU
> by kernel itself, though it'd be the another issue.
>=20
> Opinions?

Ideally it would be nice if -m4-nofpu actually did the -U__sh3__ -D__SH4__ =
by
default, since obviously one would assume that -m4 indicates SH-4. Fixing
broken GCC behavior would seem to be a more useful practice then attempting=
 to
hack around it in the kernel (we already do enough of that!).

As a workaround for some of this stupidity, I went through and changed most=
 of
the __sh3__ and __SH4__ checks to CONFIG_CPU_SH3 and CONFIG_CPU_SH4 -- since
obviously we can't rely on GCC to be correct.

With most of that inplace, I'm able to build and boot for 2.4 (and 2.5 last
time I checked).