Re: [Qemu-devel] [PATCH 3/4] tests: fw_cfg: add reboot_timeout test case

[Laszlo Ersek]

On 04/25/19 10:15, Gerd Hoffmann wrote:
> On Wed, Apr 24, 2019 at 09:16:56AM +0800, Li Qiang wrote:
>> Thomas Huth <address@hidden> 于2019年4月24日周三 上午12:29写道：
>>
>>> Is this endianess-safe? Or do you need to byteswap reboot_timeout if the
>>> host and guest endianess does not match?
>>
>> Good question!
>>
>> IIUC, the qemu fw_cfg store the 'file' entry data just in byte stream.
> 
> No.  Integers are defined to be little endian.  See fw_cfg_add_i64() for
> example, there is an explicit cpu_to_le64() call for that.

Endianness may be defined on a case-by-case basis (i.e. if you introduce
a new named fw_cfg file, you can make its contents whatever you like);
however, the integer-adding/modifying helper functions do express a
preference for endianness. Search "include/hw/nvram/fw_cfg.h" for "endian".

Thanks
Laszlo