Hi Marciej,
On Sat, Feb 24, 2024 at 05:29:43AM +0000, Maciej W. Rozycki wrote:
> On Sat, 24 Feb 2024, Maciej W. Rozycki wrote:
>
> > > sparc32 do not support generic isa dma, so do not select the symbol.
> > > Without this fix, the following patch would break the build with a
> > > missing prototype.
> >
> > Not according to my observations, kernel/dma.c is always built for
> > GENERIC_ISA_DMA configurations, so:
> >
> > kernel/dma.c:70:5: error: no previous prototype for 'request_dma' [-Werror=missing-prototypes]
> > 70 | int request_dma(unsigned int dmanr, const char * device_id)
> > | ^~~~~~~~~~~
> > kernel/dma.c:88:6: error: no previous prototype for 'free_dma' [-Werror=missing-prototypes]
> > 88 | void free_dma(unsigned int dmanr)
> > | ^~~~~~~~
> >
> > are issued regardless (and FAOD with PARPORT_PC unset).
> >
> > I can't speak for SPARC support for ISA DMA, but it seems to me like the
> > second sentence would best be removed, as would the Fixes: tag (in favour
> > to:
> >
> > Fixes: 0fcb70851fbf ("Makefile.extrawarn: turn on missing-prototypes globally")
> >
> > I presume), and possibly the messages quoted above included instead.
Thanks, I will update in v2.
>
> Actually I think ZONE_DMA should go too (it's linked to GENERIC_ISA_DMA,
> isn't it? -- cf. commit 5ac6da669e24 ("[PATCH] Set CONFIG_ZONE_DMA for
> arches with GENERIC_ISA_DMA")), and the whole thing use:
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>
> The GENERIC_ISA_DMA option itself was added to arch/sparc/config.in with
> 2.5.31 as:
>
> define_bool CONFIG_GENERIC_ISA_DMA y
>
> despite of:
>
> define_bool CONFIG_ISA n
>
> for a reason not clear to me (BLK_DEV_FD? -- but on SPARC that uses some
> hacks to work in the absence of ISA DMA anyway).
>
> Am I missing anything here?
Nice find - the code below conforms you are right:
max_zone_pfn[ZONE_DMA] = max_low_pfn;
max_zone_pfn[ZONE_NORMAL] = max_low_pfn;
As they are set to the same value there is no smaller ZONE_DMA area.
I will add an extra patch for this in v2.
Sam
