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    SubjectRe: [PATCH] x86: Create clflush() inline, remove hardcoded wbinvd
    On Sat, Jul 21, 2007 at 12:52:26PM -0700, H. Peter Anvin wrote:
    > Muli Ben-Yehuda wrote:
    > >
    > > Mostly looks good, but see below.
    > >
    > >> diff --git a/drivers/char/agp/efficeon-agp.c b/drivers/char/agp/efficeon-agp.c
    > >> index df8da72..41f46df 100644
    > >> --- a/drivers/char/agp/efficeon-agp.c
    > >> +++ b/drivers/char/agp/efficeon-agp.c
    > >> @@ -221,7 +221,7 @@ static int efficeon_create_gatt_table(struct agp_bridge_data *bridge)
    > >> SetPageReserved(virt_to_page((char *)page));
    > >>
    > >> for (offset = 0; offset < PAGE_SIZE; offset += clflush_chunk)
    > >> - asm volatile("clflush %0" : : "m" (*(char *)(page+offset)));
    > >> + clflush((char *)page+offset);
    > >
    > > The original code flushes (*(page+offset)) whereas the new code
    > > flushes (pagee+offset). Assuming this is a bug-fix, it should go as a
    > > separate patch.
    >
    > No, it doesn't. There is a * in the inline, as there should be.

    I guess I don't follow. Compare:

    diff --git a/arch/i386/mm/pageattr.c b/arch/i386/mm/pageattr.c
    index 37992ff..cb4ded4 100644
    --- a/arch/i386/mm/pageattr.c
    +++ b/arch/i386/mm/pageattr.c
    @@ -70,10 +70,10 @@ static struct page *split_large_page(unsigned long
    address, pgprot_t prot,

    static void cache_flush_page(struct page *p)
    {
    - unsigned long adr = (unsigned long)page_address(p);
    + void *adr = page_address(p);
    int i;
    for (i = 0; i < PAGE_SIZE; i +=
    boot_cpu_data.x86_clflush_size)
    - asm volatile("clflush (%0)" :: "r" (adr + i));
    + clflush(adr+i);
    }

    Original code: clflush (adr + i).
    New code: clflush (adr + i)
    diff --git a/drivers/char/agp/efficeon-agp.c b/drivers/char/agp/efficeon-agp.c
    index df8da72..41f46df 100644
    --- a/drivers/char/agp/efficeon-agp.c
    +++ b/drivers/char/agp/efficeon-agp.c
    @@ -221,7 +221,7 @@ static int efficeon_create_gatt_table(struct agp_bridge_data *bridge)
    SetPageReserved(virt_to_page((char *)page));

    for (offset = 0; offset < PAGE_SIZE; offset += clflush_chunk)
    - asm volatile("clflush %0" : : "m" (*(char *)(page+offset)));
    + clflush((char *)page+offset);

    Original code: clflush *(page + offset)
    ^
    New code: clflush (page + offset)

    So it looks like we have a purely syntactic patch that does something
    different than the original code in one of the above places. What am I
    missing?
    Cheers,
    Muli
    -
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