Re: [PATCH] x86: Quark: Flush TLB via CR3 not CR4.PGE in setup_arch()
From: Ingo Molnar
Date: Thu Sep 25 2014 - 11:11:34 EST
* Bryan O'Donoghue <pure.logic@xxxxxxxxxxxxxxxxx> wrote:
> >It talks about:
> >+ /*
> >+ * Locate the page directory and flush the TLB.
> >+ * On Quark X1000 rewriting CR3 flushes the TLB no if/else is required
> >+ * to choose between __flush_tlb() and __flush_tlb_all()
> >+ */
> > load_cr3(swapper_pg_dir);
> > __flush_tlb_all();
> >But it is completely silent on the real reason for why we don't
> >need a Quark quirk here, which would be something like:
> > /*
> > * On Quark CPUs we still have the PGE bit set so
> > * __flush_tlb_all() is not yet doing what it says - but
> > * accidentally we have a cr3 flush here which is what is
> > * needed - so there's no need to add a Quark quirk here.
> > */
> If we're adding a comment though the first thing the comment ought to say is
> what the code does for everybody else - stuff CR3 and flush the TLB, then it
> should comment on the exception for Quark.
> * Locate the page directory and flush the TLB.
> * On Quark CPUs we still have the PGE bit set so
> * __flush_tlb_all() is not yet doing what it says - but
> * accidentally we have a cr3 flush here which is what is
> * needed - so there's no need to add a Quark quirk here.
Yeah, fair enough. You can even put the latter in parentheses, to
signal that it's all a rare case.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/