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    SubjectRe: [PATCH 1/4] printk: Allocate kernel log buffer earlier
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    On Mon, Feb 28, 2011 at 12:02 PM, Mike Travis <travis@sgi.com> wrote:
    >
    >
    > Yinghai Lu wrote:
    >>
    >> On Mon, Feb 28, 2011 at 11:23 AM, Mike Travis <travis@sgi.com> wrote:
    >>>
    >>> Yinghai Lu wrote:
    >>>>
    >>>> On 02/27/2011 04:15 AM, Ingo Molnar wrote:
    >>>>>
    >>>>> * Ingo Molnar <mingo@elte.hu> wrote:
    >>>>>
    >>>>>> You could avoid all this ugly workaround of bootmem limitations by
    >>>>>> moving the allocation to memblock_alloc() and desupporting the
    >>>>>> log_buf_len=
    >>>>>> boot parameter on non-memblock architectures.
    >>>>>
    >>>>> memblock_alloc() could return -ENOSYS on architectures that do not
    >>>>> implement it - thus enabling such optional features without ugly #ifdef
    >>>>> CONFIG_HAVE_MEMBLOCK conditionals.
    >>>>
    >>>> Mike,
    >>>>
    >>>> please check updated patch...
    >>>>
    >>>> with the memblock change, you don't need to change acpi SRAT handling
    >>>> etc
    >>>> any more.
    >>>
    >>> I had to debug a weird ACPI -> Node mapping last week and the
    >>> "improved" SRAT messages helped that considerably.  It was
    >>> far easier to spot which Node didn't have the correct assignments.
    >>> I'd submit that patch even without needing fewer (like 512 lines
    >>> max instead of 4096 lines max) bytes in the log buffer.
    >>
    >> Your current change to ACPI srat is not complete yet.
    >>
    >> you only handle x2apic entries.
    >>
    >> According to ACPI 4.0 spec, We should have mixed entries with apic
    >> entries and x2apic entries.
    >> apic entries are for apic id < 255.
    >> x2apic entries are for apic id > 255.
    >>
    >> Yinghai
    >
    > Are you sure you can run both "legacy" and "x2" apic modes in
    > the same SSI under the Intel or AMD rules?
    >
    No.

    According to ACPI 4.0 Spec:
    even the CPUs are with x2apic mode (aka pre-enabled in BIOS),
    if their apic id < 255, BIOS still need to use xapic entries for them.

    Yinghai
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