On Sat, Sep 28, 2013 at 12:49:20AM +0800, Amos Kong wrote: > # qemu -drive file=/disk0,if=none,id=v0,format=qcow2 \ > -device virtio-blk-pci,drive=v0,id=v00,multifunction=on,addr=0x04.0 > .... > > Launching guest with more than 32 virtio-blk disks, > qemu will crash, because there are too many BARs. > > This patch brings the limit of non-tcg up by a factor > of 8 (32767 / 4096), i.e. 32*8 = 256.
I re-tested with latest guest kernel (3.10.0-rc5), crash still occurred after applied this patch. 1. phys_section_add: assert(next_map.sections_nb < TARGET_PAGE_SIZE); crash 2. phys_section_add: assert(next_map.sections_nb < SHRT_MAX); crash 3. without this assert of next_map.sections_nb in phys_section_add crash occurred at register_subpage(): assert(existing->mr->subpage || existing->mr == &io_mem_unassigned); > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > Signed-off-by: Amos Kong <ak...@redhat.com> > --- > exec.c | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/exec.c b/exec.c > index 5aef833..f639c01 100644 > --- a/exec.c > +++ b/exec.c > @@ -763,11 +763,18 @@ void phys_mem_set_alloc(void *(*alloc)(ram_addr_t)) > > static uint16_t phys_section_add(MemoryRegionSection *section) > { > - /* The physical section number is ORed with a page-aligned > - * pointer to produce the iotlb entries. Thus it should > - * never overflow into the page-aligned value. > - */ > - assert(next_map.sections_nb < TARGET_PAGE_SIZE); > + if (tcg_enabled()) { > + /* The physical section number is ORed with a page-aligned > + * pointer to produce the iotlb entries. Thus it should > + * never overflow into the page-aligned value. > + */ > + assert(next_map.sections_nb < TARGET_PAGE_SIZE); > + } else { > + /* For KVM or Xen we can use the full range of the ptr field > + * in PhysPageEntry. > + */ > + assert(next_map.sections_nb < SHRT_MAX); > + } > > if (next_map.sections_nb == next_map.sections_nb_alloc) { > next_map.sections_nb_alloc = MAX(next_map.sections_nb_alloc * 2, > -- > 1.8.3.1 > -- Amos.