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To: Feng Li <lifeng1519@gmail.com>, David Marchand <david.marchand@redhat.com>
Cc: Li Feng <fengli@smartx.com>, Kyle Zhang <kyle@smartx.com>,
 dev <dev@dpdk.org>, fanyang@smartx.com
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From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
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Date: Tue, 21 Apr 2020 13:19:06 +0100
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Subject: Re: [dpdk-dev] [PATCH] eal: add madvise to avoid dump memory
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On 21-Apr-20 12:06 PM, Feng Li wrote:
> #include <sys/mman.h>
> #include <time.h>
> #include <stdint.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <stdio.h>
> 
> int main(int argc, char** argv) {
>      // FIXME(fengli): XXXXX
>      uint64_t gb = atoi(argv[1]);
>      void* ptr = mmap(0, gb << 30, PROT_NONE, MAP_PRIVATE |
> MAP_ANONYMOUS, -1, 0);
>      if (ptr == (void*)-1) {
>          perror("[-] mmap failed with MAP_PRIVATE | MAP_ANONYMOUS");
>          exit(1);
>      }
>      while(1)
>          sleep(1);
>      return 0;
> }

DONTDUMP is available since Linux 3.4. I presume our minimum kernel 
version is higher than that.

I have little idea of how dumping works, but reading the manpage for 
madvise, DONTDUMP should be the way to go here. Also, reading up on 
PROT_NONE, i can't find any references to this memory necessarily being 
excluded from core dumps.

That said, I've run the program above, and i got a core dump sized 
~100K. Do i need any special configuration to trigger core dump that 
would include that anonymous memory?

-- 
Thanks,
Anatoly