On Fri, Oct 28, 2016 at 10:06:40AM +0800, Haozhong Zhang wrote: [...] > > > diff --git a/exec.c b/exec.c > > > index 264a25f..89065bd 100644 > > > --- a/exec.c > > > +++ b/exec.c > > > @@ -1234,7 +1234,7 @@ static int64_t get_file_size(int fd) > > > } > > > > > > static void *file_ram_alloc(RAMBlock *block, > > > - ram_addr_t memory, > > > + ram_addr_t *memory, > > > const char *path, > > > Error **errp) > > > { > > > @@ -1245,6 +1245,7 @@ static void *file_ram_alloc(RAMBlock *block, > > > void *area = MAP_FAILED; > > > int fd = -1; > > > int64_t file_size; > > > + ram_addr_t mem_size = *memory; > > > > > > if (kvm_enabled() && !kvm_has_sync_mmu()) { > > > error_setg(errp, > > > @@ -1309,21 +1310,27 @@ 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; > > > > Maybe we should set *memory here and not below? > > > > Qemu currently sets the memory region size to the file size, and block > length to the aligned file size, so the code here can be changed as below: > > memory_region_set_size(block->mr, mem_size); > mem_size = HOST_PAGE_ALIGN(mem_size); > *memory = mem_size; > > The second line is necessary because Qemu currently passes the aligned > file size to file_ram_alloc().
That would duplicate the existing HOST_PAGE_ALIGN logic from qemu_ram_alloc_from_file(), won't it? I believe that's yet another reason to check file size before initializing the memory region, instead of initializing it first, and fixing up its size later. -- Eduardo