Re: [Qemu-devel] [PATCH] migratioin/ram: leave RAMBlock->bmap blank on allocating

[Wei Yang <richardw.yang@linux.intel.com>]

On Mon, Jun 03, 2019 at 01:40:13PM +0800, Peter Xu wrote:
>
>Ah I see, thanks for the pointer.  Then I would agree it's fine.
>
>I'm not an expert of TCG - I'm curious on why all those three dirty
>bitmaps need to be set at the very beginning.  IIUC at least the VGA
>bitmap should not require that (so IMHO we should be fine to have all
>zeros with VGA bitmap for ramblocks, and we only set them when the
>guest touches them).  Migration bitmap should be special somehow but I
>don't know much on TCG/TLB part I'd confess so I can't say.  In other
>words, if migration is the only one that requires this "all-1"
>initialization then IMHO we may consider to remove the other part
>rather than here in migration because that's what we'd better to be
>sure with.

I am not sure about the background here, so I didn't make a change at this
place.

>
>And even if you want to remove this, I still have two suggestions:
>
>(1) proper comment here above bmap on the above fact that although
>    bmap is not set here but it's actually set somewhere else because
>    we'll sooner or later copy all 1s from the ramblock bitmap
>
>(2) imho you can move "migration_dirty_pages = 0" into
>    ram_list_init_bitmaps() too to let them be together
>

I will address these two comments and send v2.

Thanks.

>-- 
>Peter Xu

-- 
Wei Yang
Help you, Help me