Re: [Qemu-arm] [Qemu-devel] [RFC] memory: use memory_region_init_ram() instead of memory_region_allocate_system_memory()

[Igor Mammedov]

On Fri, 15 Feb 2019 15:48:43 +0100
Paolo Bonzini <address@hidden> wrote:

> On 15/02/19 12:33, Igor Mammedov wrote:
> > On Thu, 14 Feb 2019 19:11:27 +0100
> > Paolo Bonzini <address@hidden> wrote:
> > 
> >> On 14/02/19 15:07, Igor Mammedov wrote:
> >>> Also some boards (ab)use memory_region_allocate_system_memory(), calling 
> >>> it several
> >>> times to allocate various fixed sized chunks of RAM and ROMs, which is 
> >>> problematic
> >>> to map to a single initial RAM Machine::memdev backend and is currently 
> >>> broken if
> >>> -mem-path points to a not hugepage pool.
> >>
> >> This is certainly a good idea.  However, I'm not sure why you would need
> >> a memdev property on the Machine instead of just allowing 1 -numa node,
> >> which is what really is.
> > 
> > using '-numa node' would be confusing to user when he/she is not interested 
> > in numa usecase
> > it also would enable numa fdt/acpi parts generated automatically (fixable 
> > but then again
> > it adds more to confusion) and in the end there are boards that do not 
> > support numa at all
> > (s390x).
> 
> Fair enough.
> 
> What about -m, too?  Then you'd specify a memdev instead of the initial
> memory size.
that somewhat what I've planned,
make -m X translate into -object 
memory-backend-ram,id=magically-get-what-board-uses-now,size=X -machine 
memdev=thatid

one more reason for memdev vs device is that -numa now uses memdevs and so far 
it
doesn't look that non-numa initial RAM would get immediate benefits from using 
-device
on most boards (well, I couldn't come up with any modulo backend/frontend 
consistent usage)

> 
> Paolo
>