[U-Boot] [PATCH] arch/arm: Add individual TLB size support.

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Albert,

On Thu, 11 Sep 2014 17:55:00 +0200, Albert ARIBAUD
<albert.u.boot@aribaud.net> wrote:

> Hi Li.Xiubo at freescale.com,
> 
> On Wed, 10 Sep 2014 03:10:27 +0000, "Li.Xiubo at freescale.com"
> <Li.Xiubo@freescale.com> wrote:
> 
> > Hi Albert,
> > 
> > > Subject: Re: [PATCH] arch/arm: Add individual TLB size support.
> > > 
> > > Hi Xiubo,
> > > 
> > > On Mon, 7 Jul 2014 13:19:11 +0800, Xiubo Li <Li.Xiubo@freescale.com>
> > > wrote:
> > > 
> > > > This adds CONFIG_TLB_SIZE for individual board, whose TLB size maybe
> > > > larger than PGTABLE_SIZE.
> > > >
> > > > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
> > > > ---
> > > >  arch/arm/lib/board.c | 4 ++++
> > > >  1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
> > > > index dc34190..b7327ce 100644
> > > > --- a/arch/arm/lib/board.c
> > > > +++ b/arch/arm/lib/board.c
> > > > @@ -353,7 +353,11 @@ void board_init_f(ulong bootflag)
> > > >
> > > >  #if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
> > > >  	/* reserve TLB table */
> > > > +#ifdef CONFIG_TLB_SIZE
> > > > +	gd->arch.tlb_size = CONFIG_TLB_SIZE;
> > > > +#else
> > > >  	gd->arch.tlb_size = PGTABLE_SIZE;
> > > > +#endif
> > > >  	addr -= gd->arch.tlb_size;
> > > >
> > > >  	/* round down to next 64 kB limit */
> > > 
> > > There is no code in current mainline which defines CONFIG_TLB_SIZE;
> > > that makes the patch a dead code addition.
> > >
> > 
> > Yes, this will be used by our LS1 SoC first, and it is still doing
> > The upstream.
> 
> Then please sumbit this patch as part of the LS1 SoC support series,
> where the code it creates will actually be used.
>  
> > > Besides, what's the point of this as opposed to, e.g., just defining the
> > > right PGTABLE_SIZE, or renaming PGTABLE_SIZE as CONFIG_TLB_SIZE?
> > > 
> > 
> > We'll add the LPAE support in uboot and need more space for tlb.
> 
> I still don't get it. Is gd->arch.tlb_size the size of a page table or
> of a translation lookahead buffer?

Ping on both points. Meanwhile I've put the patch in 'Changes
Requested' state.

> > Thanks very much,
> > 
> > BRs
> > Xiubo
> 
> Amicalement,

Amicalement,
-- 
Albert.