Re: [PATCH] x86: Quark: Flush TLB via CR3 not CR4.PGE in setup_arch()

From: Bryan O'Donoghue
Date: Thu Sep 25 2014 - 11:05:07 EST


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.
*/

Right?

OK.

IMO.

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.
*/

?
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