Re: [Qemu-devel] [PATCH] exec.c: Ensure right alignment also for file backed ram

[Dominik Dingel]

On Thu, 24 Mar 2016 12:35:10 +0100
Paolo Bonzini <address@hidden> wrote:

> 
> 
> On 23/03/2016 22:32, Dominik Dingel wrote:
> > -    page_size = qemu_fd_getpagesize(fd);
> > -    block->mr->align = page_size;
> > +    alignment = MAX(qemu_fd_getpagesize(fd), QEMU_VMALLOC_ALIGN);
> > +    block->mr->align = alignment;
> >  
> > -    if (memory < page_size) {
> > +    if (memory < alignment) {
> >          error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
> > -                   "or larger than page size 0x%" PRIx64,
> > -                   memory, page_size);
> > +                   "or larger than needed alignment 0x%" PRIx64,
> > +                   memory, alignment);
> >          goto error;
> >      }
> 
> Why is this part necessary?  On x86 you can have 1 megabyte of RAM,
> but QEMU_VMALLOC_ALIGN is 2MB.

You are right, I changed this to keep the change consistent and thought 
the use case of x86 guests with 1 MB RAM might be a little bit obscure.

Will change this, and keep the page_size check here, and resend a new version
in the next days.

Thanks
        Dominik