Re: [Qemu-devel] [PATCH v2 0/5] fw_cfg_test refactor and add two test cases

[Li Qiang <liq3ea@gmail.com>]

Thomas Huth <thuth@redhat.com> 于2019年4月25日周四 下午5:57写道：

> On 24/04/2019 16.06, Li Qiang wrote:
> > In the disscuss of adding reboot timeout test case:
> > https://lists.gnu.org/archive/html/qemu-devel/2019-04/msg03304.html
> >
> > Philippe suggested we should uses the only related option for one
> > specific test. However currently we uses one QTestState for all the
> > test cases. In order to achieve Philippe's idea, I split the test case
> > for its own QTestState. As this patchset has changed a lot, I don't bump
> > the version.
> >
> > Change since v1:
> > Add a patch to store the reboot_timeout as little endian
> > Fix the endian issue per Thomas's review
>
> The test still aborts on a big endian host:
>
> $ QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64 tests/fw_cfg-test
> /x86_64/fw_cfg/signature: OK
> /x86_64/fw_cfg/id: OK
> /x86_64/fw_cfg/uuid: OK
> /x86_64/fw_cfg/ram_size: OK
> /x86_64/fw_cfg/nographic: OK
> /x86_64/fw_cfg/nb_cpus: OK
> /x86_64/fw_cfg/max_cpus: OK
> /x86_64/fw_cfg/numa: OK
> /x86_64/fw_cfg/boot_menu: OK
> /x86_64/fw_cfg/reboot_timeout: **
>
> ERROR:/home/thuth/devel/qemu/tests/fw_cfg-test.c:190:test_fw_cfg_reboot_timeout:
> assertion failed (reboot_timeout == 15): (251658240 == 15)
> Aborted
>
> 251658240 is 0x0F000000, i.e. a byte-swapped 0xf = 15 ... i.e. you still
> got an endianess issue somewhere in the code.
>


Hmmmm,

I have thought a long time, still can't point where is wrong.

Let's from the result:
0x0f000000 in the big endian laid as this:
low ---> high
0x0f 00 00 00

As I have swapped before the compare so it is read as this:
low ---> high
00 00 00 0x0f

However from the store side:
the 15 in big endian is:
low ---> high
00 00 00 0x0f

But Before I store it, I convert it to little endian, so following should
be stored:
low ---> high
0x0f 00 00 00

Do you apply the patch 3 and recompile the qemu binary?
If it is, I may need your help as I have no big endian host device.

You can debug and  inspect the memory layout and point out where is wrong.

Thanks,
Li Qiang







>
>  Thomas
>