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    SubjectRe: Linux 2.6.28-rc8

    * Linus Torvalds <torvalds@linux-foundation.org> wrote:

    > On Thu, 11 Dec 2008, Ingo Molnar wrote:
    > >
    > > hm, the warning caught a couple of real bugs already. (one in some
    > > cpq driver, another was in some networking driver iirc)
    >
    > Well, one thing that does irritate me is that it scares people who
    > can't do anything about it, and probably _shouldn't_ do anything about
    > it.

    yeah - and false positives also tend to create apathy and resistence
    against kernel warnings - thus drawing tester resources away from more
    important bugs.

    > I wonder if we should just change the "Warning" message to
    > "Informational" or something. Yes, they are often real bugs. But no,
    > they're not _automatically_ bugs. Almost all the time when a warning
    > triggers, it's really just a developer who wants to know about it, it's
    > not something that a user should really care/worry about.

    ok. In this case i'd suggest we should just remove the warning. People do
    get scared by needless kernel stack dumps - no matter whether it's marked
    informational or not.

    So how about the patch below, queued up in tip/x86/debug? Arjan, what do
    you think?

    Ingo

    --------------->
    From 2dcae81e819fa5cc0e9310ef8b0c079940df3bf3 Mon Sep 17 00:00:00 2001
    From: Ingo Molnar <mingo@elte.hu>
    Date: Thu, 11 Dec 2008 21:29:51 +0100
    Subject: [PATCH] IO resources, x86: remove multi-BAR mapping sanity check

    Impact: remove a debug warning

    The ioremap() time multi-BAR map warning has been causing false positives:

    http://lkml.org/lkml/2008/12/10/432
    http://lkml.org/lkml/2008/12/11/136

    So remove it for now.

    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/mm/ioremap.c | 6 ------
    include/linux/ioport.h | 1 -
    kernel/resource.c | 38 --------------------------------------
    3 files changed, 0 insertions(+), 45 deletions(-)

    diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
    index d4c4307..421b92d 100644
    --- a/arch/x86/mm/ioremap.c
    +++ b/arch/x86/mm/ioremap.c
    @@ -220,12 +220,6 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
    return (__force void __iomem *)phys_to_virt(phys_addr);

    /*
    - * Check if the request spans more than any BAR in the iomem resource
    - * tree.
    - */
    - WARN_ON(iomem_map_sanity_check(phys_addr, size));
    -
    - /*
    * Don't allow anybody to remap normal RAM that we're using..
    */
    for (pfn = phys_addr >> PAGE_SHIFT;
    diff --git a/include/linux/ioport.h b/include/linux/ioport.h
    index 041e95a..0dde772 100644
    --- a/include/linux/ioport.h
    +++ b/include/linux/ioport.h
    @@ -174,7 +174,6 @@ extern struct resource * __devm_request_region(struct device *dev,

    extern void __devm_release_region(struct device *dev, struct resource *parent,
    resource_size_t start, resource_size_t n);
    -extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);

    #endif /* __ASSEMBLY__ */
    #endif /* _LINUX_IOPORT_H */
    diff --git a/kernel/resource.c b/kernel/resource.c
    index 4337063..4b0bc70 100644
    --- a/kernel/resource.c
    +++ b/kernel/resource.c
    @@ -829,41 +829,3 @@ static int __init reserve_setup(char *str)
    }

    __setup("reserve=", reserve_setup);
    -
    -/*
    - * Check if the requested addr and size spans more than any slot in the
    - * iomem resource tree.
    - */
    -int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
    -{
    - struct resource *p = &iomem_resource;
    - int err = 0;
    - loff_t l;
    -
    - read_lock(&resource_lock);
    - for (p = p->child; p ; p = r_next(NULL, p, &l)) {
    - /*
    - * We can probably skip the resources without
    - * IORESOURCE_IO attribute?
    - */
    - if (p->start >= addr + size)
    - continue;
    - if (p->end < addr)
    - continue;
    - if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
    - PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))
    - continue;
    - printk(KERN_WARNING "resource map sanity check conflict: "
    - "0x%llx 0x%llx 0x%llx 0x%llx %s\n",
    - (unsigned long long)addr,
    - (unsigned long long)(addr + size - 1),
    - (unsigned long long)p->start,
    - (unsigned long long)p->end,
    - p->name);
    - err = -1;
    - break;
    - }
    - read_unlock(&resource_lock);
    -
    - return err;
    -}

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