[Qemu-devel] [PATCH 0/3] hostmem-file: make option 'size' optional

[Haozhong Zhang]

This patch series is mostly the followup of patch 3 in
"[PATCH v2 0/3] Improve truncation behavior of memory-backend-file" [1][2].

For certain usages of memory-backend-file, users simply want to use
the entire backend file (specified by the "mem-path" option). Therefore,
it's not necessary in such cases to specify the file size via the
"size" option. This patch series makes the "size" option of
memory-backend-file optional. In detail,

1. if the size of the backend file is not zero and the "size" option
   is not present, QEMU will use the file size as the "size" option;

2. if the backend file is a non-existing file, an empty file, or a
   directory, the "size" option is still needed;

3. the "size" option is also needed in cases that QEMU fails to the
   backend file size.

Patch 1 is not quite relevant. It adds missing comments on errors
of get_file_size() per Eduardo's suggestion.

Patch 2 moves the file operations from file_ram_alloc() to
qemu_ram_alloc_from_file(), so that all checks on the file size and
the "size" option, and the related operations on ram block length can
be put in qemu_ram_alloc_from_file() and no duplication is needed.

Patch 3 actually implements the logic to make the option "size" optional.

[1] https://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg06823.html
[2] https://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg00251.html

Haozhong Zhang (3):
  exec.c: add comment for errors of get_file_size()
  exec.c: move file operations to qemu_ram_alloc_from_file()
  hostmem-file: make option 'size' optional

 backends/hostmem-file.c |  28 ++++--
 exec.c                  | 242 ++++++++++++++++++++++++++++++------------------
 2 files changed, 170 insertions(+), 100 deletions(-)

-- 
2.10.1