On 1/5/2021 11:27 AM, Daniel P. Berrangé wrote:
> On Tue, Jan 05, 2021 at 07:41:53AM -0800, Steve Sistare wrote:
>> Allocate anonymous memory using memfd_create if the memfd-alloc option is
>> set.
>>
>> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
>> ---
>> exec.c | 38 ++++++++++++++++++++++++++++++--------
>> include/sysemu/sysemu.h | 1 +
>> qemu-options.hx | 11 +++++++++++
>> softmmu/vl.c | 4 ++++
>> trace-events | 1 +
>> 5 files changed, 47 insertions(+), 8 deletions(-)
>
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 708583b..455b43b7 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -4094,6 +4094,17 @@ SRST
>> an unmigratable state.
>> ERST
>>
>> +#ifdef __linux__
>> +DEF("memfd-alloc", 0, QEMU_OPTION_memfd_alloc, \
>> + "-memfd-alloc allocate anonymous memory using memfd_create\n",
>> + QEMU_ARCH_ALL)
>> +#endif
>> +
>> +SRST
>> +``-memfd-alloc``
>> + Allocate anonymous memory using memfd_create (Linux only).
>> +ERST
>
> Do we really need a new arg for this ? It is already possible to request
> use of memfd for the guest RAM using
>
> -object memory-backend-memfd,id=ram-node0,size=NNNN
>
> this memory backend object framework was intended to remove the need to
> add new ad-hoc CLI args for controlling memory allocation.
Yes, I considered that, but there are other memory regions that cannot be
controlled
by the command line but which must be preserved, such as vram, bios, and rom.
If vram
is not preserved, parts of the screen will be blank until the user performs
some action
which refreshes the display. bios and rom should be preserved rather than
re-recreated
with potentially different contents from the firmware images in the updated
qemu package.
However, your comment reminds me that I must add a few lines of code to
preserve the
memory-backend-memfd.
- Steve
