Re: [Qemu-devel] [PULL 08/27] hostmem-file: make option 'size' optional

[Paolo Bonzini <pbonzini@redhat.com>]

----- Original Message -----
> From: "Eduardo Habkost" <ehabkost@redhat.com>
> To: "Paolo Bonzini" <pbonzini@redhat.com>
> Cc: qemu-devel@nongnu.org, "Haozhong Zhang" <haozhong.zhang@intel.com>
> Sent: Monday, October 31, 2016 7:20:10 PM
> Subject: Re: [Qemu-devel] [PULL 08/27] hostmem-file: make option 'size' optional
> 
> On Mon, Oct 31, 2016 at 03:37:24PM +0100, Paolo Bonzini wrote:
> [...]
> > @@ -1309,21 +1317,27 @@ static void *file_ram_alloc(RAMBlock *block,
> >  
> >      file_size = get_file_size(fd);
> >  
> > -    if (memory < block->page_size) {
> > +    if (!mem_size && file_size > 0) {
> > +        mem_size = file_size;
> > +        memory_region_set_size(block->mr, mem_size);
> > +    }
> > +
> > +    if (mem_size < block->page_size) {
> >          error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to
> >          "
> >                     "or larger than page size 0x%zx",
> > -                   memory, block->page_size);
> > +                   mem_size, block->page_size);
> >          goto error;
> >      }
> >  
> > -    if (file_size > 0 && file_size < memory) {
> > +    if (file_size > 0 && file_size < mem_size) {
> >          error_setg(errp, "backing store %s size %"PRId64
> >                     " does not match 'size' option %"PRIu64,
> > -                   path, file_size, memory);
> > +                   path, file_size, mem_size);
> >          goto error;
> >      }
> >  
> > -    memory = ROUND_UP(memory, block->page_size);
> > +    mem_size = ROUND_UP(mem_size, block->page_size);
> > +    *memory = mem_size;
> 
> I suggested not touching *memory unless it was zero, and setting
> it to the memory region size, not the rounded-up size. Haozhong
> said this was going to be changed.
> 
> This will have the side-effect of setting block->used_length and
> block->max_length to the rounded up size in
> qemu_ram_alloc_from_file() (instead of the original memory region
> size). I don't know what could be the consequences of that.
> 
> This patch also skip HOST_PAGE_ALIGN-ing mem_size after getting
> the file size, which would be different from the behavior when
> size is specified explicitly. (And I also don't know the
> consequences of that)
> 
> Considering that this pull request failed to build, I suggest
> waiting for a new version from Haozhong.

Yes, I'll drop these three patches.

Paolo