On Fri, May 10, 2013 at 3:28 AM, Zhang Yanfei <zhangyan...@cn.fujitsu.com> wrote: > 于 2013年05月10日 17:27, Yinghai Lu 写道: >> On Fri, May 10, 2013 at 2:01 AM, Zhang Yanfei >> <zhangyan...@cn.fujitsu.com> wrote: >>> init_memory_mapping will set max_pfn_mapped: >>> int_memory_mapping >>> --> add_pfn_range_mapped >>> --> max_pfn_mapped = max(max_pfn_mapped, end_pfn) >>> >>> In init_mem_mapping, before we set max_pfn_mapped to 0, we >>> have already called init_memory_mapping to setup pagetable >>> for [0, ISA_END_ADDRESS], and that sets max_pfn_mapped. So >>> the assignment to 0 is not necessary, remove it. >> >> NAK. >> >> for 32bit or Xen, max_pfn_mapped is set way before in head_32.S and >> xen-enlighen. > > Hi Yinghai > > I might be wrong, but just from the code in init_mem_mapping only: > > 410 /* the ISA range is always mapped regardless of memory holes */ > 411 init_memory_mapping(0, ISA_END_ADDRESS); > 412 > 413 /* xen has big range in reserved near end of ram, skip it at > first.*/ > 414 addr = memblock_find_in_range(ISA_END_ADDRESS, end, PMD_SIZE, > PMD_SIZE); > 415 real_end = addr + PMD_SIZE; > 416 > 417 /* step_size need to be small so pgt_buf from BRK could cover it > */ > 418 step_size = PMD_SIZE; > 419 max_pfn_mapped = 0; /* will get exact value next */ > > Line 411 set max_pfn_mapped, and then line 419 set it to zero again, so > why keep the later assignment?
the comment says: /* will get exact value next */ For x86 32bit path, and xen set bigger max_pfn_mapped before. Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
