Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Fri, 13 May 2022 08:56:33 +0200 | Subject | Re: [PATCH] m68k: math-emu: Fix dependencies of math emulation support |
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Hi Greg,
On Fri, May 13, 2022 at 1:23 AM Greg Ungerer <gerg@uclinux.org> wrote: > On 11/5/22 22:54, Geert Uytterhoeven wrote: > > On Wed, May 11, 2022 at 11:48 AM Geert Uytterhoeven > > <geert@linux-m68k.org> wrote: > >> If CONFIG_M54xx=y, CONFIG_MMU=y, and CONFIG_M68KFPU_EMU=y: > >> > >> {standard input}:272: Error: invalid instruction for this architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001, 68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32 [68330, 68331, 68332, 68333, 68334, 68336, 68340, 68341, 68349, 68360], fidoa [fido]) -- statement `sub.b %d1,%d3' ignored > >> {standard input}:609: Error: invalid instruction for this architecture; needs 68020 or higher (68020 [68k, 68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060]) -- statement `bfextu 4(%a1){%d0,#8},%d0' ignored > >> {standard input}:752: Error: operands mismatch -- statement `mulu.l 4(%a0),%d3:%d0' ignored > >> {standard input}:1155: Error: operands mismatch -- statement `divu.l %d0,%d3:%d7' ignored > >> > >> The math emulation support code is intended for 68020 and higher, and > >> uses several instructions or instruction modes not available on coldfire > >> or 68000. > >> > >> Originally, the dependency of M68KFPU_EMU on MMU was fine, as MMU > >> support was only available on 68020 or higher. But this assumption > >> was broken by the introduction of MMU support for M547x and M548x. > >> > >> Drop the dependency on MMU, as the code should work fine on 68020 and up > >> without MMU (which are not yet supported by Linux, though). > >> Add dependencies on M68K_CLASSIC (to rule out Coldfire) and FPU (to rule > >> out 68xxx below 68020). > >> > >> Fixes: 1f7034b9616e6f14 ("m68k: allow ColdFire 547x and 548x CPUs to be built with MMU enabled") > >> Reported-by: kernel test robot <lkp@intel.com> > >> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> > >> --- > >> To be queued in the m68k for-v5.19 branch. > >> > >> arch/m68k/Kconfig.cpu | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/arch/m68k/Kconfig.cpu b/arch/m68k/Kconfig.cpu > >> index 16ea9a67723c09dc..9abddbbee819f1d3 100644 > >> --- a/arch/m68k/Kconfig.cpu > >> +++ b/arch/m68k/Kconfig.cpu > >> @@ -327,7 +327,7 @@ comment "Processor Specific Options" > >> > >> config M68KFPU_EMU > >> bool "Math emulation support" > >> - depends on MMU > >> + depends on M68K_CLASSIC && FPU > > ^^^^^^^^^^^^ > > Whoops, that's a silly typo... > > Are you going to resend, or are you thinking of changing the way this is done?
I was going to resend, with the above fixed, and an improved patch description w.r.t. the dependency on FPU.
> I had thought that CONFIG_FPU enabled meant you had some type of > floating point support in the kernel - be it hardware or software emulated. > So I don't have a problem with this "as is".
That matches my understanding, too.
BTW, I'm not familiar with Coldfire FPU support. Does it rely on any emulation (e.g. for transcendental functions, like '040/'060)? Would there be any point in making the math emulation code Coldfire-proof?
Thanks!
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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