Re: [Qemu-devel] [PATCH] oslib-posix: Print errors before aborting on qemu_alloc_stack()

[Philippe Mathieu-Daudé]

On 08/29/2017 06:20 PM, Eduardo Habkost wrote:

If QEMU is running on a system that's out of memory and mmap()
fails, QEMU aborts with no error message at all, making it hard
to debug the reason for the failure.

Add perror() calls that will print error information before
aborting.

Signed-off-by: Eduardo Habkost <ehabk...@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4...@amsat.org>

---
  util/oslib-posix.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index cacf0ef..80086c5 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -530,6 +530,7 @@ void *qemu_alloc_stack(size_t *sz)
      ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE,
                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
      if (ptr == MAP_FAILED) {
+        perror("failed to allocate memory for stack");
          abort();
      }

@@ -544,6 +545,7 @@ void *qemu_alloc_stack(size_t *sz)

      guardpage = ptr;
  #endif
      if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
+        perror("failed to set up stack guard page");
          abort();
      }