Re: [Qemu-stable] [Qemu-devel] [PATCH] vl: Delay initialization of memory backends

[Eduardo Habkost]

On Wed, Aug 31, 2016 at 02:47:21PM -0700, address@hidden wrote:
[...]
> GTESTER check-qtest-x86_64
> qemu-system-x86_64: Failed initializing vhost-user memory map, consider using 
> -object memory-backend-file share=on
> qemu-system-x86_64: vhost_set_mem_table failed: Success (0)
[...]
> **
> ERROR:/tmp/qemu-test/src/tests/vhost-user-test.c:149:wait_for_fds: assertion 
> failed: (s->fds_num)

Ouch. It looks like the ordering requirements are messier than I
thought. vhost-user depends on the memory backends to be already
initialized.

We can't use early initialization because prealloc delays chardev
init too much. We can't delay initialization because it is done
after netdevs.

We _really_ need to change this to simply use the ordering used
on the command-line/config instead of hardcoding messy ordering
requirements, but I wouldn't like to wait for a QemuOpts
refactoring to fix the bug. I will take a look at the memory
regions initialization path, and try to trigger the
memory-backend prealloc code there.

-- 
Eduardo