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Re: [Xen-devel] [PATCH v5 03/17] xenctx: Add -n (--display-stack-pages) option to output larger stack

On 03/24/14 06:39, Ian Campbell wrote:
On Sat, 2014-03-22 at 16:49 -0400, Don Slutz wrote:
As you can see from above, only the last 3 lines show up for "-n 3"

Why is the SP moving around in these pictures? I understood that this
option was changing what was considered to be the limit of the stack,
not the stack pointer itself, so shouldn't it be the base of the stack
which is moving around?
These are pictures of the same stack at 3 different times.  And as you
can see
from above, this option does change the stack limit.
There was no stack limit shown on your diagrams, only a stack pointer
which was mysteriously changing. The SP is an actual register which is a
property of the VM, changing it based on a xenctx surely doesn't make
sense! (also it is not moving by page sized increments, which is odd
even for the base, which ought to point at a page boundary surely).

Perhaps if you had the diagram once and along side it had columns
showing what is printed for each -n value as a range

                                None     -n 1
         +------------------+              +
         |                  |              |
         |                  |              |
         |                  |              |
         |                  |              |
         |                  |              |
         +------------------+     +        |
         |                  |     |        |
SP --> |                  |     +        +
         |                  |
         |                  |
         |                  |

(or whatever the reality is)

I will add this.  And some statement about each picture is for a
different time.
Wait, what? Each picture is for a different time? How is that useful?

The point of these diagrams is surely to illustrate the effect of what
using this option would be at some fixed "snapshot" in time, adding a
second axis of variation to the pictures is just confusing.


Ok, will adjust to just 1 picture.

   -Don Slutz

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