Re: [Qemu-devel] [PATCH] q35: split memory at 2G

[Eric Blake <eblake@redhat.com>]

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On 5/28/19 3:48 PM, Gerd Hoffmann wrote:
> Original q35 behavior was to split memory 2.75 GB, leaving space for the

s/memory/memory at/

> mmconfig bar at 0xb000000 and pci I/O window starting at 0xc0000000.
> 
> Note: Those machine types have been removed from the qemu codebase
> meanwhile because they could not be live-migrated so there was little
> value in keeping them around.
> 
> With the effort to allow for gigabyte-alignment of guest memory that
> behavior was changed:  The split was moved to 2G, but only in case the
> memory didn't fit below 2.75 GB.
> 
> So today the address space between 2G and 2,75G is not used for guest
> memory in typical use cases, where the guest memory sized at a power of

s/memory/memory is/

> two or a gigabyte number.  But if you configure your guest with some odd
> amout of memory (such as 2.5G) the address space is used.

s/amout/amount/

> 
> This patch removes that oddity for 4.1+ machine types.  The memory is
> splitted at 2G no matter what.

s/splitted/split/

> 
> Cc: László Érsek <lersek@redhat.com>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  include/hw/i386/pc.h | 1 +
>  hw/i386/pc.c         | 1 +
>  hw/i386/pc_q35.c     | 7 ++++++-
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org


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