Re: [Qemu-devel] [PATCH 04/12] arch_init: introduce ram_page_save()

["Michael R. Hines" <mrhines@linux.vnet.ibm.com>]

On 07/25/2013 04:18 PM, Lei Li wrote:
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>   arch_init.c |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 58 insertions(+), 0 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index a8b91ee..a418071 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -699,6 +699,64 @@ static uint64_t ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
>       return remaining_size;
>   }
>
> +/* This is the last block from where we have sent data for local migration */
> +static RAMBlock *last_block_local;
> +static ram_addr_t last_offset_local;
> +
> +static int ram_page_save(QEMUFile *f)
> +{
> +    RAMBlock *block = last_block_local;
> +    ram_addr_t offset = last_offset_local;
> +    MemoryRegion *mr = block->mr;
> +    int bytes_sent = 0;
> +
> +    if (!block) {
> +        block = QTAILQ_FIRST(&ram_list.blocks);
> +    }
> +
> +    do {
> +        mr = block->mr;
> +        uint8_t *p;
> +        int cont = (block == last_block_local) ? RAM_SAVE_FLAG_CONTINUE : 0;
> +
> +        p = memory_region_get_ram_ptr(mr) + offset;
> +
> +        if (is_zero_page(p)) {
> +            qemu_put_be64(f, offset | cont | RAM_SAVE_FLAG_COMPRESS);
> +            if (!cont) {
> +                qemu_put_byte(f, strlen(block->idstr));
> +                qemu_put_buffer(f, (uint8_t *)block->idstr,
> +                                strlen(block->idstr));
> +            }
> +            qemu_put_byte(f, *p);
> +            bytes_sent = 1;
> +        } else {
> +            qemu_put_be64(f, offset | cont | RAM_SAVE_FLAG_PAGE);
> +            if (!cont) {
> +                qemu_put_byte(f, strlen(block->idstr));
> +                qemu_put_buffer(f, (uint8_t *)block->idstr,
> +                                strlen(block->idstr));
> +            }
> +            qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> +            bytes_sent = TARGET_PAGE_SIZE;
> +        }
> +
> +        offset += TARGET_PAGE_SIZE;
> +        if (offset >= block->length) {
> +            offset = 0;
> +            block = QTAILQ_NEXT(block, next);
> +            if (!block) {
> +                block = QTAILQ_FIRST(&ram_list.blocks);
> +            }
> +        }
> +    } while (block != last_block_local || offset != last_offset_local);
> +
> +    last_block_local = block;
> +    last_offset_local = offset;
> +
> +    return bytes_sent;
> +}
> +
>   static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
>   {
>       int ret, rc = 0;

Seems like there's a lot of duplicate code.

We have new hooks to override the way memory is saved in arch_init.c

See the QEMUFileOps......... save_page() / before_ram_iterate() / 
after_ram_iterate()

You might need to introduce a new "load_page()" pointer in QEMUFileOps.

Then all this code can be private to migration-local.c

- Michael