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SubjectThis kernel requires the following features not present on the CPU... (on a VIA C7 CPU)
Hello,

I have got a VIA EPIA EX15000G Mini-ITX mainboard with a C7 VIA Esther
processor (1500MHz).
There are two options in the BIOS that affect CPU feature flags:

C7 CMPXCHG8 - enable/disable (Disable to install windows NT 4.0) and
C7 No Execute (NX) - enable/disable

I enabled both and compiled a new 2.6.22-rc1-mm1 kernel. So far so good.

The problem is that the system is very unstable and crashes regularly
(1-3 times a day).
After a crash the bios resets the two processor flags back to disabled.
But like this
the kernel complains and does not continiue booting:

> This kernel requires the following features not present on the CPU:
> 0:8

Each time this happens, I have to go to the BIOS and manually enable
these flags again.
That is pretty annoying! :(
I attached a cpuinfo.txt. When the two flags are disabled, cx8 and nx
are not listed there.


Now my question is:

Would it be possible to override the BIOS settings of cx8 and nx and
activate it with linux anyway?
The CPU supports it and I don't see any reason to disable it.


I already wrote several emails to VIA months ago saying that this is
probably a bug in their BIOS, but they
are neitherreleasing a new BIOS nor reacting in any way. Their so called
support website viaarena.com
is not helping neither. Since VIA is not helping at all, the only
soulution I see would be to override the
BIOS'es decision.

Concerning the crashes I already changed the memory module, but with no
success. I'm not sure
wether this is a hardware or software bug.


Many regards,
claas
processor : 0
vendor_id : CentaurHauls
cpu family : 6
model : 10
model name : VIA Esther processor 1500MHz
stepping : 9
cpu MHz : 799.952
cache size : 128 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge cmov pat clflush acpi mmx fxsr sse sse2 nx pni est rng rng_en ace ace_en ace2 ace2_en phe phe_en pmm pmm_en
bogomips : 1601.30
clflush size : 64

000000 (gap: 3bf00000:a4100000)
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 243571
Kernel command line: root=/dev/sda3 ro quiet
mapped APIC to ffffd000 (fee00000)
mapped IOAPIC to ffffc000 (fec00000)
Enabling fast FPU save and restore... done.
Enabling unmasked SIMD FPU exception support... done.
Initializing CPU#0
PID hash table entries: 4096 (order: 12, 16384 bytes)
Detected 1499.916 MHz processor.
Console: colour VGA+ 80x25
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes)
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes)
Memory: 969928k/981952k available (1931k kernel code, 11472k reserved, 659k data, 192k init, 64448k highmem)
virtual kernel memory layout:
fixmap : 0xfffaa000 - 0xfffff000 ( 340 kB)
pkmap : 0xff800000 - 0xffc00000 (4096 kB)
vmalloc : 0xf8800000 - 0xff7fe000 ( 111 MB)
lowmem : 0xc0000000 - 0xf8000000 ( 896 MB)
.init : 0xc038a000 - 0xc03ba000 ( 192 kB)
.data : 0xc02e2c3b - 0xc03879d4 ( 659 kB)
.text : 0xc0100000 - 0xc02e2c3b (1931 kB)
Checking if this processor honours the WP bit even in supervisor mode... Ok.
Calibrating delay using timer specific routine.. 3002.19 BogoMIPS (lpj=5001917)
Mount-cache hash table entries: 512
CPU: After generic identify, caps: 87c9bbff 00100000 00000000 00000000 00000081 00000000 00000000
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 128K (64 bytes/line)
CPU: After all inits, caps: 07c9bbff 00100000 00000000 00000000 00000081 00003fcc 00000000
Compat vDSO mapped to ffffe000.
CPU: Centaur VIA Esther processor 1500MHz stepping 09
Checking 'hlt' instruction... OK.
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