fd_write_vmcore() will indefinitely spin for a non-blocking
file-descriptor that would block. However, if the fd is non-blocking,
how does it make sense to spin?

Change this behavior to return an error instead.

Note that this can only happen with an fd provided by a management
application. The fd opened internally by dump-guest-memory is blocking.

While there, also fix 'writen_size' variable name.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

Signed-off-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>

dump.c was recently added to the code. It unconditionally
includes sys/procfs which is not available with MinGW (w32, w64).

It looks like this file is not needed at all (tested on Linux),
so I removed it completely.

Some other include statements are also redundant because they are
already included in qemu-common, therefore they were removed, too.
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

This simplifies things, because they will only be included for softmmu
targets and because the stubs are taken out-of-line in separate files,
which in the future could even be compiled only once.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

So that it can use the same prototype in both cases.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The command's usage:
   dump-guest-memory [-p] protocol [begin] [length]
The supported protocol can be file or fd:
1. file: the protocol starts with "file:", and the following string is
   the file's path.
2. fd: the protocol starts with "fd:", and the following string is the
   fd's name.

Note:
  1. If you want to use gdb to process the core, please specify -p option.
     The reason why the -p option is not default is:
       a. guest machine in a catastrophic state can have corrupted memory,
          which we cannot trust.
       b. The guest machine can be in read-mode even if paging is enabled.
          For example: the guest machine uses ACPI to sleep, and ACPI sleep
          state goes in real-mode.
  2. If you don't want to dump all guest's memory, please specify the start
     physical address and the length.
Signed-off-by: NWen Congyang <wency@cn.fujitsu.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>