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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Cannot boot PVH dom0 with big initrd
On Fri, Feb 13, 2026 at 09:40:31PM +0100, Roger Pau Monné wrote: > On Fri, Feb 13, 2026 at 04:56:39PM +0100, Roger Pau Monné wrote: > > On Fri, Feb 13, 2026 at 09:56:42AM +0100, Jan Beulich wrote: > > > On 13.02.2026 05:02, Marek Marczykowski-Górecki wrote: > > > > Hi, > > > > > > > > After fixing the xhci crash, I hit another issue - booting with 236MB > > > > initrd doesn't work, I get: > > > > > > > > (XEN) [ 3.151856] *** Building a PVH Dom0 *** > > > > ... > > > > (XEN) [ 3.593940] Unable to allocate memory with order 0! > > > > (XEN) [ 3.597110] Failed to setup Dom0 physical memory map > > > > (XEN) [ 3.599884] > > > > (XEN) [ 3.602482] **************************************** > > > > (XEN) [ 3.605272] Panic on CPU 0: > > > > (XEN) [ 3.607928] Could not construct d0 > > > > (XEN) [ 3.610692] **************************************** > > > > (XEN) [ 3.613463] > > > > (XEN) [ 3.616035] Reboot in five seconds... > > > > (XEN) [ 8.626565] Resetting with ACPI MEMORY or I/O RESET_REG. > > > > > > > > Full console log: > > > > https://gist.github.com/marmarek/c9dbc87bf07b76f2899781755762f565 > > > > > > > > If I skip initrd, then it boots just fine (but dom0 is not happy about > > > > that). 164MB initrd failed too, but 13MB started ok. > > > > Just in case, I tried skipping XHCI console, but it didn't change > > > > anything. > > > > > > > > Host has 16GB of memory, and there is no dom0_mem= parameter. Xen is > > > > started from GRUB, using MB2+EFI. > > > > > > Hmm, yes, there's an ordering issue: Of course we free initrd space (as > > > used > > > for passing from the boot loader to Xen) only after copying to the > > > designated > > > guest area. Yet dom0_compute_nr_pages(), intentionally, includes the > > > space in > > > its calculation (adding initial_images_nrpages()'s return value). PV Dom0 > > > isn't affected because to load huge initrd there, the kernel has to > > > request > > > the initrd to not be mapped into the initial allocation. > > > > Right, on PV dom0 we do not copy the image to a new set of pages, we > > simply assign the pages where the initrd resides to the domain. We > > can't populate those pages in the p2m as-is, otherwise we would > > shatter super pages. > > > > I think the fix below should do it, it's likely the best we can do. > > Can you please give it a try Marek? > > > > Thanks, Roger. > > --- > > diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c > > index 0b467fd4a4fc..8e3cb5d0db76 100644 > > --- a/xen/arch/x86/dom0_build.c > > +++ b/xen/arch/x86/dom0_build.c > > @@ -343,7 +343,7 @@ unsigned long __init dom0_compute_nr_pages( > > > > for_each_node_mask ( node, dom0_nodes ) > > avail += avail_domheap_pages_region(node, 0, 0) + > > - initial_images_nrpages(node); > > + is_pv_domain(d) ? initial_images_nrpages(node) : 0; > > > > /* Reserve memory for further dom0 vcpu-struct allocations... */ > > avail -= (d->max_vcpus - 1UL) > > I'm working on a more complex patch, that attempts to account the > memory used by the init images towards the reserved amount that's kept > by Xen. This should make accounting a bit better, in that we won't > end up reserving the Xen memory plus the memory used by the init > images. > > It's still however a WIP, but would you mind giving it a try? This one worked :) (XEN) [ 4.014243] Dom0 memory allocation stats: (XEN) [ 4.017378] order 0 allocations: 4 (XEN) [ 4.020111] order 1 allocations: 3 (XEN) [ 4.022758] order 2 allocations: 4 (XEN) [ 4.025406] order 3 allocations: 4 (XEN) [ 4.028150] order 4 allocations: 3 (XEN) [ 4.030886] order 5 allocations: 2 (XEN) [ 4.033602] order 6 allocations: 2 (XEN) [ 4.036305] order 7 allocations: 6 (XEN) [ 4.039020] order 8 allocations: 6 (XEN) [ 4.041597] order 9 allocations: 5 (XEN) [ 4.044261] order 10 allocations: 9 (XEN) [ 4.046831] order 11 allocations: 7 (XEN) [ 4.049493] order 12 allocations: 9 (XEN) [ 4.052147] order 13 allocations: 7 (XEN) [ 4.054799] order 14 allocations: 6 (XEN) [ 4.057447] order 15 allocations: 7 (XEN) [ 4.060080] order 16 allocations: 7 (XEN) [ 4.062609] order 17 allocations: 5 (XEN) [ 4.065227] order 18 allocations: 9 (XEN) [ 4.921719] ELF: phdr: paddr=0x200000 memsz=0x1ff3928 (XEN) [ 4.924403] ELF: phdr: paddr=0x2200000 memsz=0x1c00000 (XEN) [ 4.927079] ELF: memory: 0x200000 -> 0x3e00000 (XEN) [ 4.929759] ELF: note: PHYS32_RELOC align: 0x200000 min: 0x200000 max: 0x3fffffff (XEN) [ 4.932884] ELF: note: PHYS32_ENTRY = 0x16a2ca0 (XEN) [ 4.935921] ELF: note: GUEST_OS = "linux" (XEN) [ 4.938953] ELF: note: GUEST_VERSION = "2.6" (XEN) [ 4.942005] ELF: note: XEN_VERSION = "xen-3.0" (XEN) [ 4.945077] ELF: note: VIRT_BASE = 0xffffffff80000000 (XEN) [ 4.948133] ELF: note: INIT_P2M = 0x8000000000 (XEN) [ 4.951203] ELF: note: ENTRY = 0xffffffff82d3c160 (XEN) [ 4.954221] ELF: note: FEATURES = "!writable_page_tables" (XEN) [ 4.957229] ELF: note: PAE_MODE = "yes" (XEN) [ 4.960175] ELF: note: L1_MFN_VALID (XEN) [ 4.962775] ELF: note: MOD_START_PFN = 0x1 (XEN) [ 4.965675] ELF: note: PADDR_OFFSET = 0 (XEN) [ 4.968540] ELF: note: SUPPORTED_FEATURES = 0x8801 (XEN) [ 4.971420] ELF: note: LOADER = "generic" (XEN) [ 4.974303] ELF: note: SUSPEND_CANCEL = 0x1 (XEN) [ 4.977186] ELF: Found PVH image (XEN) [ 4.979910] ELF: addresses: (XEN) [ 4.982237] virt_base = 0x0 (XEN) [ 4.984694] elf_paddr_offset = 0x0 (XEN) [ 4.987141] virt_offset = 0x0 (XEN) [ 4.989599] virt_kstart = 0x200000 (XEN) [ 4.992044] virt_kend = 0x3e00000 (XEN) [ 4.994498] virt_entry = 0x16a2ca0 (XEN) [ 4.996966] p2m_base = 0x8000000000 (XEN) [ 4.999415] ELF: phdr 0 at 0x200000 -> 0x21f3928 (XEN) [ 5.007160] ELF: phdr 1 at 0x2200000 -> 0x3e00000 (XEN) [ 5.055448] Dom0 memory map: (XEN) [ 5.057763] [0000000000000000, 000000000009efff] (usable) (XEN) [ 5.060281] [000000000009f000, 00000000000fffff] (reserved) (XEN) [ 5.062812] [0000000000100000, 000000005471afff] (usable) (XEN) [ 5.065324] [000000005471b000, 000000005475bfff] (reserved) (XEN) [ 5.067891] [000000005475c000, 0000000063c2dfff] (usable) (XEN) [ 5.070446] [0000000063c2e000, 000000006d17afff] (reserved) (XEN) [ 5.073036] [000000006d17b000, 000000006d22bfff] (ACPI data) (XEN) [ 5.075649] [000000006d22c000, 000000006d2ebfff] (ACPI NVS) (XEN) [ 5.078267] [000000006d2ec000, 000000006fffefff] (reserved) (XEN) [ 5.080908] [000000006ffff000, 000000006ffffdcb] (usable) (XEN) [ 5.083560] [000000006ffffdcc, 000000006ffffe97] (ACPI data) (XEN) [ 5.086243] [0000000070000000, 00000000807fffff] (reserved) (XEN) [ 5.088943] [00000000c0000000, 00000000cfffffff] (reserved) (XEN) [ 5.091662] [00000000fe000000, 00000000fe010fff] (reserved) (XEN) [ 5.094413] [00000000fec00000, 00000000fec00fff] (reserved) (XEN) [ 5.097193] [00000000fed00000, 00000000fed00fff] (reserved) (XEN) [ 5.099976] [00000000fed20000, 00000000fed7ffff] (reserved) (XEN) [ 5.102779] [00000000fee00000, 00000000fee00fff] (reserved) (XEN) [ 5.105615] [00000000ff000000, 00000001023fffff] (reserved) (XEN) [ 5.108487] [0000000102400000, 000000045c89cfff] (usable) (XEN) [ 5.111354] [000000045c89d000, 000000047f7fffff] (unusable) (XEN) [ 5.114263] Initial low memory virq threshold set at 0x4000 pages. (XEN) [ 5.117108] Scrubbing Free RAM in background -- Best Regards, Marek Marczykowski-Górecki Invisible Things Lab Attachment:
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