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* [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
@ 2019-01-12  8:16 guoren
  2019-01-15 15:36 ` Christoph Hellwig
  0 siblings, 1 reply; 7+ messages in thread
From: guoren @ 2019-01-12  8:16 UTC (permalink / raw)
  To: palmer, aou; +Cc: linux-arch, linux-riscv, linux-kernel, Guo Ren, Mao Han

From: Guo Ren <ren_guo@c-sky.com>

max_low_pfn should be pfn_size not byte_size.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Signed-off-by: Mao Han <mao_han@c-sky.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
---
 arch/riscv/kernel/setup.c | 2 +-
 arch/riscv/mm/init.c      | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index fc8006a..5463e67 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -174,7 +174,7 @@ static void __init setup_bootmem(void)
 	BUG_ON(mem_size == 0);
 
 	set_max_mapnr(PFN_DOWN(mem_size));
-	max_low_pfn = memblock_end_of_DRAM();
+	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
 
 #ifdef CONFIG_BLK_DEV_INITRD
 	setup_initrd();
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 1d9bfaf..658ebf6 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -28,7 +28,8 @@ static void __init zone_sizes_init(void)
 	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
 
 #ifdef CONFIG_ZONE_DMA32
-	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G, max_low_pfn));
+	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G,
+			(unsigned long) PFN_PHYS(max_low_pfn)));
 #endif
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 
-- 
2.7.4


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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-12  8:16 [PATCH] riscv: fixup max_low_pfn with PFN_DOWN guoren
@ 2019-01-15 15:36 ` Christoph Hellwig
  2019-01-15 16:10   ` Guo Ren
  0 siblings, 1 reply; 7+ messages in thread
From: Christoph Hellwig @ 2019-01-15 15:36 UTC (permalink / raw)
  To: guoren
  Cc: linux-arch, aou, palmer, linux-kernel, Mao Han, Guo Ren, linux-riscv

On Sat, Jan 12, 2019 at 04:16:27PM +0800, guoren@kernel.org wrote:
> From: Guo Ren <ren_guo@c-sky.com>
> 
> max_low_pfn should be pfn_size not byte_size.
> 
> Signed-off-by: Guo Ren <ren_guo@c-sky.com>
> Signed-off-by: Mao Han <mao_han@c-sky.com>
> Cc: Palmer Dabbelt <palmer@sifive.com>
> Cc: Albert Ou <aou@eecs.berkeley.edu>
> ---
>  arch/riscv/kernel/setup.c | 2 +-
>  arch/riscv/mm/init.c      | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index fc8006a..5463e67 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -174,7 +174,7 @@ static void __init setup_bootmem(void)
>  	BUG_ON(mem_size == 0);
>  
>  	set_max_mapnr(PFN_DOWN(mem_size));
> -	max_low_pfn = memblock_end_of_DRAM();
> +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());

I know it is used just above, but can we please just switch this
code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
obsfucates what is going on?

>  
>  #ifdef CONFIG_BLK_DEV_INITRD
>  	setup_initrd();
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 1d9bfaf..658ebf6 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -28,7 +28,8 @@ static void __init zone_sizes_init(void)
>  	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
>  
>  #ifdef CONFIG_ZONE_DMA32
> -	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G, max_low_pfn));
> +	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G,
> +			(unsigned long) PFN_PHYS(max_low_pfn)));
>  #endif

Same comment as above here, plus I think we should just use
memblock_end_of_DRAM directly, e.g. something like:

static const phys_addr_t max_dma32_addr = 4UL * SZ_1G;

	max_zone_pfns[ZONE_DMA32] =
		min(memblock_end_of_DRAM(), max_dma32_addr) >> PAGE_SHIFT;


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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-15 15:36 ` Christoph Hellwig
@ 2019-01-15 16:10   ` Guo Ren
  2019-01-15 16:12     ` Christoph Hellwig
  0 siblings, 1 reply; 7+ messages in thread
From: Guo Ren @ 2019-01-15 16:10 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: linux-arch, aou, palmer, linux-kernel, Mao Han, Guo Ren, linux-riscv

On Tue, Jan 15, 2019 at 07:36:13AM -0800, Christoph Hellwig wrote:
> On Sat, Jan 12, 2019 at 04:16:27PM +0800, guoren@kernel.org wrote:
> > From: Guo Ren <ren_guo@c-sky.com>
> > 
> > max_low_pfn should be pfn_size not byte_size.
> > 
> > Signed-off-by: Guo Ren <ren_guo@c-sky.com>
> > Signed-off-by: Mao Han <mao_han@c-sky.com>
> > Cc: Palmer Dabbelt <palmer@sifive.com>
> > Cc: Albert Ou <aou@eecs.berkeley.edu>
> > ---
> >  arch/riscv/kernel/setup.c | 2 +-
> >  arch/riscv/mm/init.c      | 3 ++-
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > index fc8006a..5463e67 100644
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -174,7 +174,7 @@ static void __init setup_bootmem(void)
> >  	BUG_ON(mem_size == 0);
> >  
> >  	set_max_mapnr(PFN_DOWN(mem_size));
> > -	max_low_pfn = memblock_end_of_DRAM();
> > +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
> 
> I know it is used just above, but can we please just switch this
> code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
> obsfucates what is going on?
???
#define PFN_DOWN(x)	((x) >> PAGE_SHIFT)

phys_addr_t __init_memblock memblock_end_of_DRAM(void)
{
	int idx = memblock.memory.cnt - 1;

	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
}

What's the problem? PFN_DOWN() couldn't be used with function call?

> 
> >  
> >  #ifdef CONFIG_BLK_DEV_INITRD
> >  	setup_initrd();
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 1d9bfaf..658ebf6 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -28,7 +28,8 @@ static void __init zone_sizes_init(void)
> >  	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
> >  
> >  #ifdef CONFIG_ZONE_DMA32
> > -	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G, max_low_pfn));
> > +	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G,
> > +			(unsigned long) PFN_PHYS(max_low_pfn)));
> >  #endif
> 
> Same comment as above here, plus I think we should just use
> memblock_end_of_DRAM directly, e.g. something like:
> 
> static const phys_addr_t max_dma32_addr = 4UL * SZ_1G;
> 
> 	max_zone_pfns[ZONE_DMA32] =
> 		min(memblock_end_of_DRAM(), max_dma32_addr) >> PAGE_SHIFT;
Em... The meaning of PFN_PHYS(max_low_pfn) != memblock_end_of_DRAM() in
32-bit highmem system. Of cause, riscv doesn't support highmem, so I
think memblock_end_of_DRAM() is also OK.

But...

static void __init zone_sizes_init(void)
{
	unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };

#ifdef CONFIG_ZONE_DMA32
	max_zone_pfns[ZONE_DMA32] = PFN_DOWN(min(4UL * SZ_1G, max_low_pfn));
#endif
	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;

	free_area_init_nodes(max_zone_pfns);
}

The max_low_pfn also used by ZONE_NORMAL, So shall we need change that?
	max_zone_pfns[ZONE_NORMAL] = PFN_DOWN(memblock_end_of_DRAM());
                                     ^^^^^^^^ also must >> PAGE_SHIFT?

My patch just want to point out that max_low_pfn is PFN not size. In fact
there is no error for running without my patch :P

Best Regards
 Guo Ren

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-15 16:10   ` Guo Ren
@ 2019-01-15 16:12     ` Christoph Hellwig
  2019-01-16  1:07       ` Guo Ren
  0 siblings, 1 reply; 7+ messages in thread
From: Christoph Hellwig @ 2019-01-15 16:12 UTC (permalink / raw)
  To: Guo Ren
  Cc: linux-arch, aou, palmer, linux-kernel, Mao Han,
	Christoph Hellwig, Guo Ren, linux-riscv

On Wed, Jan 16, 2019 at 12:10:00AM +0800, Guo Ren wrote:
> > >  	set_max_mapnr(PFN_DOWN(mem_size));
> > > -	max_low_pfn = memblock_end_of_DRAM();
> > > +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
> > 
> > I know it is used just above, but can we please just switch this
> > code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
> > obsfucates what is going on?
> ???
> #define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
> 
> phys_addr_t __init_memblock memblock_end_of_DRAM(void)
> {
> 	int idx = memblock.memory.cnt - 1;
> 
> 	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
> }
> 
> What's the problem? PFN_DOWN() couldn't be used with function call?

PFN_DOWN gives you the correct result.  But I think it actually
drastically reduces readability over just opencoding it.

> My patch just want to point out that max_low_pfn is PFN not size. In fact
> there is no error for running without my patch :P

No, I think your patch is correct.  I just wonder if we could make
the code easier to read.

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-15 16:12     ` Christoph Hellwig
@ 2019-01-16  1:07       ` Guo Ren
  2019-01-24  2:00         ` Palmer Dabbelt
  0 siblings, 1 reply; 7+ messages in thread
From: Guo Ren @ 2019-01-16  1:07 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: linux-arch, aou, palmer, linux-kernel, Mao Han, Guo Ren, linux-riscv

Hi Christoph,

I use PFN_DOWN() every where as possible and seems it's a habit
problem. So let risc-v maintainer to choose "PFN_DOW()" or
">> PAGE_SHIFT".

Also the same with "end_of_DRAM & max_low_pfn".

Best Regards
 Guo Ren

On Tue, Jan 15, 2019 at 08:12:54AM -0800, Christoph Hellwig wrote:
> On Wed, Jan 16, 2019 at 12:10:00AM +0800, Guo Ren wrote:
> > > >  	set_max_mapnr(PFN_DOWN(mem_size));
> > > > -	max_low_pfn = memblock_end_of_DRAM();
> > > > +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
> > > 
> > > I know it is used just above, but can we please just switch this
> > > code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
> > > obsfucates what is going on?
> > ???
> > #define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
> > 
> > phys_addr_t __init_memblock memblock_end_of_DRAM(void)
> > {
> > 	int idx = memblock.memory.cnt - 1;
> > 
> > 	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
> > }
> > 
> > What's the problem? PFN_DOWN() couldn't be used with function call?
> 
> PFN_DOWN gives you the correct result.  But I think it actually
> drastically reduces readability over just opencoding it.
> 
> > My patch just want to point out that max_low_pfn is PFN not size. In fact
> > there is no error for running without my patch :P
> 
> No, I think your patch is correct.  I just wonder if we could make
> the code easier to read.

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-16  1:07       ` Guo Ren
@ 2019-01-24  2:00         ` Palmer Dabbelt
  2019-01-24  2:31           ` Guo Ren
  0 siblings, 1 reply; 7+ messages in thread
From: Palmer Dabbelt @ 2019-01-24  2:00 UTC (permalink / raw)
  To: guoren
  Cc: linux-arch, aou, linux-kernel, mao_han, Christoph Hellwig,
	ren_guo, linux-riscv

On Tue, 15 Jan 2019 17:07:38 PST (-0800), guoren@kernel.org wrote:
> Hi Christoph,
>
> I use PFN_DOWN() every where as possible and seems it's a habit
> problem. So let risc-v maintainer to choose "PFN_DOW()" or
> ">> PAGE_SHIFT".
>
> Also the same with "end_of_DRAM & max_low_pfn".

PFN_DOWN makes sense to me, as that's what we're trying to do here (round a 
physical address down to page frame number).  Am a I misunderstanding 
something?

>
> Best Regards
>  Guo Ren
>
> On Tue, Jan 15, 2019 at 08:12:54AM -0800, Christoph Hellwig wrote:
>> On Wed, Jan 16, 2019 at 12:10:00AM +0800, Guo Ren wrote:
>> > > >  	set_max_mapnr(PFN_DOWN(mem_size));
>> > > > -	max_low_pfn = memblock_end_of_DRAM();
>> > > > +	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
>> > >
>> > > I know it is used just above, but can we please just switch this
>> > > code to use >> PAGE_SHIFT instead of PFN_DOWN, which just horribly
>> > > obsfucates what is going on?
>> > ???
>> > #define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
>> >
>> > phys_addr_t __init_memblock memblock_end_of_DRAM(void)
>> > {
>> > 	int idx = memblock.memory.cnt - 1;
>> >
>> > 	return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size);
>> > }
>> >
>> > What's the problem? PFN_DOWN() couldn't be used with function call?
>>
>> PFN_DOWN gives you the correct result.  But I think it actually
>> drastically reduces readability over just opencoding it.
>>
>> > My patch just want to point out that max_low_pfn is PFN not size. In fact
>> > there is no error for running without my patch :P
>>
>> No, I think your patch is correct.  I just wonder if we could make
>> the code easier to read.

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linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] riscv: fixup max_low_pfn with PFN_DOWN.
  2019-01-24  2:00         ` Palmer Dabbelt
@ 2019-01-24  2:31           ` Guo Ren
  0 siblings, 0 replies; 7+ messages in thread
From: Guo Ren @ 2019-01-24  2:31 UTC (permalink / raw)
  To: Palmer Dabbelt
  Cc: linux-arch, aou, linux-kernel, mao_han, Christoph Hellwig,
	ren_guo, linux-riscv

On Wed, Jan 23, 2019 at 06:00:35PM -0800, Palmer Dabbelt wrote:
> On Tue, 15 Jan 2019 17:07:38 PST (-0800), guoren@kernel.org wrote:
> >Hi Christoph,
> >
> >I use PFN_DOWN() every where as possible and seems it's a habit
> >problem. So let risc-v maintainer to choose "PFN_DOW()" or
> >">> PAGE_SHIFT".
> >
> >Also the same with "end_of_DRAM & max_low_pfn".
> 
> PFN_DOWN makes sense to me, as that's what we're trying to do here (round a
> physical address down to page frame number).  Am a I misunderstanding
> something?
>
No, you got it :)

Best Regards
 Guo Ren

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^ permalink raw reply	[flat|nested] 7+ messages in thread

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Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-12  8:16 [PATCH] riscv: fixup max_low_pfn with PFN_DOWN guoren
2019-01-15 15:36 ` Christoph Hellwig
2019-01-15 16:10   ` Guo Ren
2019-01-15 16:12     ` Christoph Hellwig
2019-01-16  1:07       ` Guo Ren
2019-01-24  2:00         ` Palmer Dabbelt
2019-01-24  2:31           ` Guo Ren

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