On Fri, 19 Nov 2010, Shaohui Zheng wrote: > > > > > Index: linux-hpe4/arch/x86/kernel/e820.c > > > > > =================================================================== > > > > > --- linux-hpe4.orig/arch/x86/kernel/e820.c 2010-11-15 17:13:02.483461667 +0800 > > > > > +++ linux-hpe4/arch/x86/kernel/e820.c 2010-11-15 17:13:07.083461581 +0800 > > > > > @@ -971,6 +971,7 @@ > > > > > } > > > > > > > > > > static int userdef __initdata; > > > > > +static u64 max_mem_size __initdata = ULLONG_MAX; > > > > > > > > > > /* "mem=nopentium" disables the 4MB page tables. */ > > > > > static int __init parse_memopt(char *p) > > > > > @@ -989,12 +990,28 @@ > > > > > > > > > > userdef = 1; > > > > > mem_size = memparse(p, &p); > > > > > - e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1); > > > > > + e820_remove_range(mem_size, max_mem_size - mem_size, E820_RAM, 1); > > > > > + max_mem_size = mem_size; > > > > > > > > > > return 0; > > > > > } > > > > > > > > This needs memmap= support as well, right? > > > we did not do the testing after combine both memmap and numa=hide paramter, > > > I think that the result should similar with mem=XX, they both remove a memory > > > region from the e820 table. > > > > > > > You've modified the parser for mem= but not memmap= so the change needs > > additional support for the latter. > > > > the parser for mem= is not modified, the changed parser is numa=, I add a addtional > option numa=hide=. > The above hunk is modifying the x86 parser for the mem= parameter. > > Your patchset doesn't do that, I'm talking specifically about the amount > > of memory left behind so that the kernel at least still boots. That seems > > to be a function of e820_hide_mem() to do some sanity checking so we > > actually still get a kernel rather than the responsibility of the > > command-line parser. > > How much memory is enough to make sure the kernel can still boot, it is very > hard to measure. it is almost impossible to get the exact data. I try to leave very > few memory to kernel(hide most memory with numa=hide), it cause a panic directly. > > I have no idea about it, do you have any suggestions? > Yes, I think we should use FAKE_NODE_MIN_SIZE to represent the smallest node that may be added and so the appropriate behavior or e820_hide_mem() would be to leave at least this quantity behind for the kernel to be loaded. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>