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

[Markus Armbruster]

Haozhong Zhang <address@hidden> writes:

> 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.

"fails to the backend file size": are you missing a verb?

> 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(-)