freebsd stable - Apr 2008 - kvm_open: kvm_nlist: No such file or directory

A few weeks ago I did a source upgrade from 6.2 to 7-STABLE.  I didn't 
"make delete-old" so a bunch of old libraries and such were left lying
around causing problems when I rebuilt all my ports.  I'd read about some 
recent improvements to DDB and SCHED_ULE in 7-STABLE, and it's a miserable 
snowy weekend in Seattle right now, so I decided I'd take this opportunity 
to update my system to the latest 7-STABLE and get rid of those old 
libraries properly this time.

Now sysutils/wmmemmon and sysutils/wmcpuload stopped working.
Both die with:
kvm_open: kvm_nlist: No such file or directory
error extracting symbols

I found two PRs for other ports (ascpu and wmcube-gdk) to fix similar 
problems, but they seem to be related to 8-CURRENT.  The solution in both 
of these cases is to use sysctls instead of using kvm.
PR numbers are 119923 and 120142.

My question is should the existing code work in 7-STABLE or do wmmemmon 
and wmcpuload need to be changed to use sysctls?
They worked for me for a couple of weeks on 7-STABLE, but like I said, I 
had old libraries lying around and some of the windowmaker stuff 
chose to link to them.
I have since cleaned up my system and rebuilt (I believe) everything and 
now the ports no longer work.

This is what I believe is the offending code snippet from 
sysutils/wmmemmon's mem_freebsd.c file:
--------------------------------------------------------------
static kvm_t *kvm_data = NULL;
static int pageshift;
static struct nlist nlst[] = { {"_cp_time"}, {"_cnt"}, {0}
};

/* initialize function */
void mem_init(void)
{
     int pagesize = getpagesize();
     pageshift = 0;

     while (pagesize > 1) {
    pageshift++;
    pagesize >>= 1;
     }

     kvm_data = kvm_open(NULL, NULL, NULL, O_RDONLY, "kvm_open");

     if (kvm_data == NULL) {
    fprintf(stderr, "can't open kernel virtual memory");
    exit(1);
     }
     kvm_nlist(kvm_data, nlst);

     if (nlst[0].n_type == 0 || nlst[1].n_type == 0) {
    fprintf(stderr, "error extracting symbols");
    exit(1);
     }

On Sunday 20 April 2008 01:38:32 pm Luke Dean wrote:
> A few weeks ago I did a source upgrade from 6.2 to 7-STABLE.  I didn't
> "make delete-old" so a bunch of old libraries and such were left
lying
> around causing problems when I rebuilt all my ports.  I'd read about
some
> recent improvements to DDB and SCHED_ULE in 7-STABLE, and it's a
miserable
> snowy weekend in Seattle right now, so I decided I'd take this
opportunity
> to update my system to the latest 7-STABLE and get rid of those old
> libraries properly this time.
>
> Now sysutils/wmmemmon and sysutils/wmcpuload stopped working.
> Both die with:
> kvm_open: kvm_nlist: No such file or directory
> error extracting symbols
>
> I found two PRs for other ports (ascpu and wmcube-gdk) to fix similar
> problems, but they seem to be related to 8-CURRENT.  The solution in both
> of these cases is to use sysctls instead of using kvm.
> PR numbers are 119923 and 120142.
>
> My question is should the existing code work in 7-STABLE or do wmmemmon
> and wmcpuload need to be changed to use sysctls?
> They worked for me for a couple of weeks on 7-STABLE, but like I said, I
> had old libraries lying around and some of the windowmaker stuff
> chose to link to them.
> I have since cleaned up my system and rebuilt (I believe) everything and
> now the ports no longer work.
>
> This is what I believe is the offending code snippet from
> sysutils/wmmemmon's mem_freebsd.c file:
Yes, cp_time[] is no more.  Make them use the sysctl (kern.cp_time) instead.
> --------------------------------------------------------------
> static kvm_t *kvm_data = NULL;
> static int pageshift;
> static struct nlist nlst[] = { {"_cp_time"}, {"_cnt"},
{0} };
>
> /* initialize function */
> void mem_init(void)
> {
>      int pagesize = getpagesize();
>      pageshift = 0;
>
>      while (pagesize > 1) {
>     pageshift++;
>     pagesize >>= 1;
>      }
>
>      kvm_data = kvm_open(NULL, NULL, NULL, O_RDONLY, "kvm_open");
>
>      if (kvm_data == NULL) {
>     fprintf(stderr, "can't open kernel virtual memory");
>     exit(1);
>      }
>      kvm_nlist(kvm_data, nlst);
>
>      if (nlst[0].n_type == 0 || nlst[1].n_type == 0) {
>     fprintf(stderr, "error extracting symbols");
>     exit(1);
>      }
>
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-- 
John Baldwin