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SubjectRe: [RFC PATCH] memory driver: make phys_index/end_phys_index reflect the start/end section number
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On Thu, 2014-04-03 at 09:37 +0800, Zhang Yanfei wrote:
> Add ccing
>
> On 04/02/2014 04:56 PM, Li Zhong wrote:
> > I noticed the phys_index and end_phys_index under
> > /sys/devices/system/memory/memoryXXX/ have the same value, e.g.
> > (for the test machine, one memory block has 8 sections, that is
> > sections_per_block equals 8)
> >
> > # cd /sys/devices/system/memory/memory100/
> > # cat phys_index end_phys_index
> > 00000064
> > 00000064
> >
> > Seems they should reflect the start/end section number respectively, which
> > also matches what is said in Documentation/memory-hotplug.txt
>
Hi Yanfei,

Thanks for the review.

> Indeed. I've noticed this before. The value in 'end_phys_index' doesn't
> match what it really means. But, the name itself is vague, it looks like
> it is the index of some page frame. (we keep this name for compatibility?)

I guess so, Dave just reminded me that the RFC would also break
userspace..

And now my plan is:
leave the code unchanged
update the document, state the end_phys_index/phys_index are the same,
and means the memory block index
[optional] create two new files start_sec_nr, end_sec_nr if needed

Do you have any other suggestions?

Thanks, Zhong

>
> The corresponding member in struct memory_block is:
>
> struct memory_block {
> unsigned long start_section_nr;
> unsigned long end_section_nr;
> ...
>
> The two members seem to have the right name, and have the right value in kernel.
>
>
> >
> > This patch tries to modify that so the two files could show the start/end
> > section number of the memory block.
> >
> > After this change, output of the above example looks like:
> >
> > # cat phys_index end_phys_index
> > 00000320
> > 00000327
> >
> > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
> > ---
> > drivers/base/memory.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> > index bece691..b10f2fa 100644
> > --- a/drivers/base/memory.c
> > +++ b/drivers/base/memory.c
> > @@ -114,7 +114,7 @@ static ssize_t show_mem_start_phys_index(struct device *dev,
> > struct memory_block *mem = to_memory_block(dev);
> > unsigned long phys_index;
> >
> > - phys_index = mem->start_section_nr / sections_per_block;
> > + phys_index = mem->start_section_nr;
> > return sprintf(buf, "%08lx\n", phys_index);
> > }
> >
> > @@ -124,7 +124,7 @@ static ssize_t show_mem_end_phys_index(struct device *dev,
> > struct memory_block *mem = to_memory_block(dev);
> > unsigned long phys_index;
> >
> > - phys_index = mem->end_section_nr / sections_per_block;
> > + phys_index = mem->end_section_nr;
> > return sprintf(buf, "%08lx\n", phys_index);
> > }
> >
> >
> >
> > --
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>




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