[Xen-devel] About the behavior on an illegal dom0_mem value

[INAKOSHI Hiroya <inakoshi.hiroya@xxxxxxxxxxxxxx>]

Hi, all,

I would like to ask for comments about what behavior you think
appropriate when they supply dom0_mem parameter with a large value
exceeding the size of physical memory.  The current behavior is that a
system stops with warnings and then it reboots.  Attached is the
console log when the system stopped.


There are at least three options, including the current behavior:

1/ Boot Dom0 with the default dom0_mem value (maybe showing warnings.)
2/ Halt and never reboot.
3/ Halt and reboot (current behavior.)

I understand that the current behavior (halt and reboot) is the
ordinary way of handling errors caused by illegal parameters, but
repeating reboot seems not helpful to me.  So, how about #1 ?

Considering the benefit for system administrators, another option is
booting Dom0 in single user mode so that they get a chance to correct
the illegal value immediately.


Best,
Hiroya INAKOSHI


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 http://www.cl.cam.ac.uk/netos/xen
 University of Cambridge Computer Laboratory

 Xen version 3.0-unstable (root@) (gcc ?o?[?W???? 4.1.1 20060525 (Red Hat 
4.1.1-1)) 2006?N  7?? 28?ú ?à?j?ú 21:18:09 JST
 Latest ChangeSet: Thu Jul 27 14:06:15 2006 +0100 10756:5848356af8da

(XEN) Command line: /boot/xen.gz-2.6.16.13 com1=115200,8n1 console=com1 
dom0_mem=3326M
(XEN) WARNING: Only the first 4 GB of the physical memory map can be accessed
(XEN)          by Xen in 32-bit mode. Truncating the memory map...
(XEN) Physical RAM map:
(XEN)  0000000000000000 - 000000000009e000 (usable)
(XEN)  000000000009e000 - 00000000000a0000 (reserved)
(XEN)  00000000000e4000 - 0000000000100000 (reserved)
(XEN)  0000000000100000 - 00000000cfe70000 (usable)
(XEN)  00000000cfe70000 - 00000000cfe82000 (ACPI data)
(XEN)  00000000cfe82000 - 00000000cff00000 (ACPI NVS)
(XEN)  00000000cff00000 - 00000000d0000000 (reserved)
(XEN)  00000000fec00000 - 00000000fec10000 (reserved)
(XEN)  00000000fee00000 - 00000000fee01000 (reserved)
(XEN)  00000000ff000000 - 0000000100000000 (reserved)
(XEN) System RAM: 3326MB (3405880kB)
(XEN) Xen heap: 10MB (10344kB)
(XEN) Using scheduler: SMP Credit Scheduler (credit)
(XEN) PAE disabled.
(XEN) found SMP MP-table at 000f6ce0
(XEN) DMI present.
(XEN) Using APIC driver default
(XEN) ACPI: RSDP (v000 PTLTD                                 ) @ 0x000f6cb0
(XEN) ACPI: RSDT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe7bd20
(XEN) ACPI: FADT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe81e8e
(XEN) ACPI: TCPA (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe81f02
(XEN) ACPI: MCFG (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe81f34
(XEN) ACPI: MADT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe81f70
(XEN) ACPI: BOOT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe81fd8
(XEN) ACPI: SSDT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0xcfe7bd5c
(XEN) ACPI: DSDT (v001 FUJ    4LWXL    0x20300000 FUJ  0x01000000) @ 0x00000000
(XEN) ACPI: Local APIC address 0xfee00000
(XEN) ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled)
(XEN) Processor #0 15:6 APIC version 20
(XEN) ACPI: LAPIC (acpi_id[0x01] lapic_id[0x01] enabled)
(XEN) Processor #1 15:6 APIC version 20
(XEN) ACPI: LAPIC_NMI (acpi_id[0x00] high edge lint[0x1])
(XEN) ACPI: LAPIC_NMI (acpi_id[0x01] high edge lint[0x1])
(XEN) ACPI: IOAPIC (id[0x02] address[0xfec00000] gsi_base[0])
(XEN) IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 high edge)
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
(XEN) ACPI: IRQ0 used by override.
(XEN) ACPI: IRQ2 used by override.
(XEN) ACPI: IRQ9 used by override.
(XEN) Enabling APIC mode:  Flat.  Using 1 I/O APICs
(XEN) Using ACPI (MADT) for SMP configuration information
(XEN) Initializing CPU#0
(XEN) Detected 3400.266 MHz processor.
(XEN) CPU: Trace cache: 12K uops, L1 D cache: 16K
(XEN) CPU: L2 cache: 2048K
(XEN) CPU: Physical Processor ID: 0
(XEN) CPU: Processor Core ID: 0
(XEN) VMX disabled by Feature Control MSR.
(XEN) Intel machine check architecture supported.
(XEN) Intel machine check reporting enabled on CPU#0.
(XEN) CPU0: Intel P4/Xeon Extended MCE MSRs (24) available
(XEN) CPU0: Thermal monitoring enabled
(XEN) CPU0: Intel(R) Pentium(R) D CPU 3.40GHz stepping 02
(XEN) Booting processor 1/1 eip 90000
(XEN) Initializing CPU#1
(XEN) CPU: Trace cache: 12K uops, L1 D cache: 16K
(XEN) CPU: L2 cache: 2048K
(XEN) CPU: Physical Processor ID: 0
(XEN) CPU: Processor Core ID: 1
(XEN) VMX disabled by Feature Control MSR.
(XEN) Intel machine check architecture supported.
(XEN) Intel machine check reporting enabled on CPU#1.
(XEN) CPU1: Intel P4/Xeon Extended MCE MSRs (24) available
(XEN) CPU1: Thermal monitoring enabled
(XEN) CPU1: Intel(R) Pentium(R) D CPU 3.40GHz stepping 02
(XEN) Total of 2 processors activated.
(XEN) ENABLING IO-APIC IRQs
(XEN)  -> Using new ACK method
(XEN) ..TIMER: vector=0xF0 apic1=0 pin1=2 apic2=-1 pin2=-1
(XEN) checking TSC synchronization across 2 CPUs: passed.
(XEN) Platform timer is 1.193MHz PIT
(XEN) Brought up 2 CPUs
(XEN) Machine check exception polling timer started.
(XEN) *** LOADING DOMAIN 0 ***
(XEN) Domain 0 kernel supports features = { 0000001f }.
(XEN) Domain 0 kernel requires features = { 00000000 }.
(XEN) PHYSICAL MEMORY ARRANGEMENT:
(XEN)  Dom0 alloc.:   03000000->04000000 (847360 pages to be allocated)
(XEN) VIRTUAL MEMORY ARRANGEMENT:
(XEN)  Loaded kernel: c0100000->c045831c
(XEN)  Init. ramdisk: c0459000->c06aba00
(XEN)  Phys-Mach map: c06ac000->c09eb800
(XEN)  Start info:    c09ec000->c09ed000
(XEN)  Page tables:   c09ed000->c09f1000
(XEN)  Boot stack:    c09f1000->c09f2000
(XEN)  TOTAL:         c0000000->c0c00000
(XEN)  ENTRY ADDRESS: c0100000
(XEN) Dom0 has maximum 2 VCPUs
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Not enough RAM for DOM0 reservation.
(XEN) ****************************************
(XEN)
(XEN) Reboot in five seconds...

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