hi, with unstable from yesterday, linux seems to have trouble detecting how much memory to use, i.e. it detects 24M even if only given 16M by the domain builder, and then it dies trying to allocate it: <5>Linux version 2.6.12.6-xenU (jacobg@jacobpad) (gcc version 3.3.6 (Gentoo 3.3.6, ssp-3.3.6-1.0, pie-8.7.8)) #5 Wed Nov 2 17:20:28 CET 2005 <6>BIOS-provided physical RAM map: Xen: 0000000000000000 - 0000000001000000 (usable) <5>24MB LOWMEM available. <7>On node 0 totalpages: 6144 <7> DMA zone: 6144 pages, LIFO batch:1 kernel BUG at mm/bootmem.c:213 (__alloc_bootmem_core)! [<c02f8cdb>] __alloc_bootmem_core+0x24b/0x3a0 [<c02f9269>] __alloc_bootmem_node+0x39/0x70 [<c02f981e>] free_area_init_core+0x2ae/0x370 [<c026c79d>] _etext+0x0/0x7f863 [<c02f99ec>] free_area_init+0x2c/0x30 [<c02f3030>] zone_sizes_init+0x30/0x40 [<c02f3654>] setup_arch+0x254/0x4b0 [<c02ec6a7>] start_kernel+0x27/0x1d0 <0>Kernel panic - not syncing: BUG! This problem is fairly recent, 16M domains worked fine a couple of weeks ago. arch/xen/i386/kernel/setup.c does not seem to have changed in any relevant ways. Jacob -- Save time and bandwidth with EDelta: http://www.diku.dk/~jacobg/edelta/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 11/3/05, Jacob Gorm Hansen <jacobg@diku.dk> wrote:> hi, > > with unstable from yesterday, linux seems to have trouble detecting > how much memory to use, i.e. it detects 24M even if only given 16M by > the domain builder, and then it dies trying to allocate it:The problem seems to be the 8M(!) slack introduced with this patch. # HG changeset patch # User kaf24@firebug.cl.cam.ac.uk # Node ID 41489189b19e20b3fda4222e1787821d990206bc # Parent c08e7f0b1ee597381d8c0dcca8a1b915b31bbc96 Add slack to balloon driver to allow to counteract low-mem address space allocations in backend drivers. Signed-off-by: Keir Fraser <keir@xensource.com> Could the 8M slack be made optional somehow? I like being able to have 16M domains... Jacob -- Save time and bandwidth with EDelta: http://www.diku.dk/~jacobg/edelta/ _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
On 3 Nov 2005, at 15:03, Jacob Gorm Hansen wrote:> # HG changeset patch > # User kaf24@firebug.cl.cam.ac.uk > # Node ID 41489189b19e20b3fda4222e1787821d990206bc > # Parent c08e7f0b1ee597381d8c0dcca8a1b915b31bbc96 > Add slack to balloon driver to allow to counteract low-mem > address space allocations in backend drivers. > Signed-off-by: Keir Fraser <keir@xensource.com> > > Could the 8M slack be made optional somehow? I like being able to have > 16M domains...The slack is in the p2m table, to balance out address space allocations by backend drivers. It''s not intended that domains allocate an extra 8M beyond what the builder allowed them. I''ll take a quick look. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
> The problem seems to be the 8M(!) slack introduced with this patch. > > # HG changeset patch > # User kaf24@firebug.cl.cam.ac.uk > # Node ID 41489189b19e20b3fda4222e1787821d990206bc > # Parent c08e7f0b1ee597381d8c0dcca8a1b915b31bbc96 > Add slack to balloon driver to allow to counteract low-mem > address space allocations in backend drivers. > Signed-off-by: Keir Fraser <keir@xensource.com> > > Could the 8M slack be made optional somehow? I like being able to have > 16M domains...With changeset 7616:6a2d93c2b32d332366cc5e8d11e85c476afa8f9b (which I just checked in) if you specify ''mem='' as a Linux boot parameter then the 8M slack in the mem_map and p2m table is disabled. So, you should be able to boot a 16M domain with no slack by adding ''mem=16M'' to its command line. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jacob Gorm Hansen
2005-Nov-04 10:53 UTC
Re: [Xen-devel] Re: Failure booting domU with < 24M
On 11/4/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:> > Could the 8M slack be made optional somehow? I like being able to have > > 16M domains... > > With changeset 7616:6a2d93c2b32d332366cc5e8d11e85c476afa8f9b (which I > just checked in) if you specify ''mem='' as a Linux boot parameter then > the 8M slack in the mem_map and p2m table is disabled.Thanks, I will have a look once this passes regression testing. Jacob _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel