Re: [PATCH v4 03/15] xenctx: Add -m (--multiple_pages) option to output larger stack

[George Dunlap <george.dunlap@eu.citrix.com>]

On 03/18/2014 10:15 PM, Don Slutz wrote:
> From: Don Slutz <Don@CloudSwitch.com>
>
> Important: This is the stack size to display not the configured
> stack size.
>
> Using pictures (for a 3 page configured system):
>
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
> SP --> |                  |
>         |                  |
>         +------------------+

Sorry, what is this a picture of?  I can't make any sense out of it.  
Shouldn't this have only one box, the next have two, and the bottom one 
have three?

>
> Display using "-m 1" since the used stack pages is 1.
>
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>         |                  |
> SP --> |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>
> Display using "-m 2" since the used stack pages is 2.
>
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
> SP --> |                  |
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         |                  |
>         +------------------+
>
> Display using "-m 3" since the used stack pages is 3.
>
> Signed-off-by: Don Slutz <Don@CloudSwitch.com>
> ---
> v4 Converted from xenctx: Add -2 (--two-pages) option to switch stack size to 8KiB
>
>   tools/xentrace/xenctx.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/tools/xentrace/xenctx.c b/tools/xentrace/xenctx.c
> index 42a47f3..6da38cc 100644
> --- a/tools/xentrace/xenctx.c
> +++ b/tools/xentrace/xenctx.c
> @@ -35,6 +35,7 @@ static struct xenctx {
>       int frame_ptrs;
>       int stack_trace;
>       int disp_all;
> +    int multiple_pages;
>       int all_vcpus;
>       int self_paused;
>       xc_dominfo_t dominfo;
> @@ -664,6 +665,8 @@ static int print_stack(vcpu_guest_context_any_t *ctx, int vcpu, int width)
>   
>       stack_limit = ((stack_pointer(ctx) + XC_PAGE_SIZE)
>                      & ~((guest_word_t) XC_PAGE_SIZE - 1));
> +    if ( xenctx.multiple_pages > 1 )
> +        stack_limit += (xenctx.multiple_pages - 1) * XC_PAGE_SIZE;
>       printf("\n");
>       printf("Stack:\n");
>       for (i=1; i<5 && stack < stack_limit; i++) {
> @@ -834,18 +837,21 @@ static void usage(void)
>           kernel_start);
>       printf("  -a, --all          display more registers\n");
>       printf("  -C, --all-vcpus    print info for all vcpus\n");
> +    printf("  -m PAGES, --multiple-pages=PAGES\n");
> +    printf("                     assume the kernel was compiled with PAGES (default 1) of stacks.\n");
>   }
>   
>   int main(int argc, char **argv)
>   {
>       int ch;
>       int ret;
> -    static const char *sopts = "fs:hak:SC";
> +    static const char *sopts = "fs:hak:SCm:";
>       static const struct option lopts[] = {
>           {"stack-trace", 0, NULL, 'S'},
>           {"symbol-table", 1, NULL, 's'},
>           {"frame-pointers", 0, NULL, 'f'},
>           {"kernel-start", 1, NULL, 'k'},
> +        {"multiple-pages", 0, NULL, 'm'},

I think I would call the long option "kernel-stack-pages" or something 
like that.  "Multiple pages" doesn't really convey much meaning.  -m is 
probably a fine short option, but -n might be more memorable.

  -George