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

[Eduardo Habkost]

On Mon, Oct 31, 2016 at 03:47:53PM -0400, Paolo Bonzini wrote:
> 
> 
> ----- Original Message -----
> > From: "Eduardo Habkost" <address@hidden>
> > To: "Paolo Bonzini" <address@hidden>
> > Cc: address@hidden, "Haozhong Zhang" <address@hidden>
> > 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.

I believe you can keep the other two (as long as the build error
is fixed). I was already going to include them in my pull
request, but removed them.

-- 
Eduardo