RFC: Output ACPI info via sysfs

RFC: Output ACPI info via sysfs

[Prarit Bhargava]

Currently, after booting a system there is no way to tell what hardware 
is currently in the system.  The current output from sysfs only 
indicates what knowledge the kernel has of the system (ie, is limited by 
NR_CPUS, etc.).  However, during ACPI initialization a lot of data is 
output to the console about the precise number of CPUs, lapics, etc.

Having this information is useful to anyone (or any application) 
interested in querying the real system information.

Any thoughts, concerns?  (Code not yet generated -- just looking for an 
okay on the RFC)

P.

Re: RFC: Output ACPI info via sysfs

[Bjorn Helgaas]

On Thursday 11 May 2006 08:57, Prarit Bhargava wrote:
> Currently, after booting a system there is no way to tell what hardware 
> is currently in the system.  The current output from sysfs only 
> indicates what knowledge the kernel has of the system (ie, is limited by 
> NR_CPUS, etc.).  However, during ACPI initialization a lot of data is 
> output to the console about the precise number of CPUs, lapics, etc.
> 
> Having this information is useful to anyone (or any application) 
> interested in querying the real system information.

Some of this we should get via "lspnp".  (But you need PNPACPI and
somebody (/me looks around innocently) should fix lspnp to look in
/sys/bus/pnp/devices.)

But I see your point about things that are often described in static
tables, like CPUs and APICs, because those don't show up in the
namespace.  Len's pmtools package[1] can already extract and decode
most of the static tables.

Does this (from a 4-CPU Intel Tiger) have some of the information
you need?

# ./acpidump -b -t APIC | ../madt/madt 
ACPI: APIC (v001 INTEL  SR870BN4 0x01072002 MSFT 0x00010013) @ 0x(nil)
ACPI: LSAPIC (acpi_id[0x00] lsapic_id[0xc6] lsapic_eid[0x18] enabled)
ACPI: LSAPIC (acpi_id[0x01] lsapic_id[0xc2] lsapic_eid[0x18] enabled)
ACPI: LSAPIC (acpi_id[0x02] lsapic_id[0xc4] lsapic_eid[0x18] enabled)
ACPI: LSAPIC (acpi_id[0x03] lsapic_id[0xc0] lsapic_eid[0x18] enabled)
ACPI: IOSAPIC (id[0x0] global_irq_base[0x0] address[0xfec00000])
ACPI: IOSAPIC (id[0x1] global_irq_base[0x18] address[0xfec10000])
ACPI: IOSAPIC (id[0x2] global_irq_base[0x30] address[0xfec20000])
ACPI: IOSAPIC (id[0x3] global_irq_base[0x48] address[0xfec30000])
ACPI: IOSAPIC (id[0x4] global_irq_base[0x60] address[0xfec40000])
ACPI: IOSAPIC (id[0x5] global_irq_base[0x78] address[0xfec50000])
ACPI: IOSAPIC (id[0x6] global_irq_base[0x90] address[0xfec60000])
ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
ACPI: PLAT_INT_SRC (low level type[0x3] id[0x00c6] eid[0x18] iosapic_vector[0x1e] global_irq[0x16]
Length 230 OK
Checksum OK


[1] ftp://ftp.kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools-20051111.tar.bz2

Re: RFC: Output ACPI info via sysfs

[Prarit Bhargava]

>   
> Does this (from a 4-CPU Intel Tiger) have some of the information
> you need?
>
>   
Yes, the lsapics are listed, which at least gives me an idea of the # of 
CPUs in the system ...

P.
> # ./acpidump -b -t APIC | ../madt/madt 
> ACPI: APIC (v001 INTEL  SR870BN4 0x01072002 MSFT 0x00010013) @ 0x(nil)
> ACPI: LSAPIC (acpi_id[0x00] lsapic_id[0xc6] lsapic_eid[0x18] enabled)
> ACPI: LSAPIC (acpi_id[0x01] lsapic_id[0xc2] lsapic_eid[0x18] enabled)
> ACPI: LSAPIC (acpi_id[0x02] lsapic_id[0xc4] lsapic_eid[0x18] enabled)
> ACPI: LSAPIC (acpi_id[0x03] lsapic_id[0xc0] lsapic_eid[0x18] enabled)
>