[U-Boot] [PATCH 2/4] net: round up before calling flush_cache

Marek Vasut
2012-04-02T01:44:39Z

Dear Mike Frysinger,

> On Sunday 01 April 2012 17:00:56 Marek Vasut wrote:
> > Dear Mike Frysinger,
> >
> > > On Sunday 01 April 2012 09:22:59 Stefano Babic wrote:
> > > > If the range passed to flush_cache is not multiple
> > > > of ARCH_DMA_MINALIGN, a warning due to mislaignment
> > > > is printed.
> > > > Detected with fec_mxc, mx35 boards:
> > > >
> > > > CACHE: Misaligned operation at range [80800000, 8083c310]
> > >
> > > warning on flushing is broken. the arch/arm/cpu/arm926ejs/cache.c code
> > > should probably be fixed instead.
> >
> > Why exactly?
>
> the flush isn't harmful (ignoring the fact that a few extra bytes might get
> written back to external memory), and the data isn't evicted from cache.
> after all, we aren't talking about invalidate here, we're talking about
> flush.

Right ... and can you be sure nothing important is overwritten in RAM?

> plus, no other arch (linux or u-boot) does this.
>
> so the better question is, why exactly should you be warning ? you should
> provide justification when doing something unusual ...

Because you can destroy data in DRAM that arrived there by DMA transfer for
example?

> -mike

Best regards,
Marek Vasut