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    SubjectRe: [patch 7/8] Add a bootparameter to reserve high linear address space.
    Andrew Morton wrote:
    > The comment says "must". If that's true then printing a what-you-did-wrong
    > message and halting is appropriate.
    >
    > But whatever. The issue is flagged and I'm happy to leave it in Jeremy's
    > lap.

    Considering I wrote that patch, I think I should fix it -- here you go
    Subject: Add a bootparameter to reserve high linear address space.

    Add a bootparameter to reserve high linear address space for hypervisors.
    This is necessary to allow dynamically loaded hypervisor modules, which
    might not happen until userspace is already running, and also provides a
    useful tool to benchmark the performance impact of reduced lowmem address
    space.

    Signed-off-by: Zachary Amsden <zach@vmware.com>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>

    ---
    Documentation/kernel-parameters.txt | 5 +++++
    arch/i386/kernel/setup.c | 19 +++++++++++++++++++
    2 files changed, 24 insertions(+)

    diff -r 5bb2fc59943d Documentation/kernel-parameters.txt
    --- a/Documentation/kernel-parameters.txt Thu Aug 03 01:36:13 2006 -0700
    +++ b/Documentation/kernel-parameters.txt Thu Aug 03 01:36:13 2006 -0700
    @@ -1357,6 +1357,11 @@ running once the system is up.

    reserve= [KNL,BUGS] Force the kernel to ignore some iomem area

    + reservetop= [IA-32]
    + Format: nn[KMG]
    + Reserves a hole at the top of the kernel virtual
    + address space.
    +
    resume= [SWSUSP]
    Specify the partition device for software suspend

    diff -r 5bb2fc59943d arch/i386/kernel/setup.c
    --- a/arch/i386/kernel/setup.c Thu Aug 03 01:36:13 2006 -0700
    +++ b/arch/i386/kernel/setup.c Thu Aug 03 01:36:52 2006 -0700
    @@ -160,6 +160,12 @@ static char command_line[COMMAND_LINE_SI
    static char command_line[COMMAND_LINE_SIZE];

    unsigned char __initdata boot_params[PARAM_SIZE];
    +
    +static int __init setup_reservetop(char *s)
    +{
    + return 1;
    +}
    +__setup("reservetop", setup_reservetop);

    static struct resource data_resource = {
    .name = "Kernel data",
    @@ -917,6 +923,17 @@ static void __init parse_cmdline_early (
    else if (!memcmp(from, "vmalloc=", 8))
    __VMALLOC_RESERVE = memparse(from+8, &from);

    + /*
    + * reservetop=size reserves a hole at the top of the kernel
    + * address space which a hypervisor can load into later.
    + * Needed for dynamically loaded hypervisors, so relocating
    + * the fixmap can be done before paging initialization.
    + */
    + else if (!memcmp(from, "reservetop=", 11)) {
    + unsigned long reserve = memparse(from+11, &from);
    + reserve_top_address(reserve);
    + }
    +
    next_char:
    c = *(from++);
    if (!c)
    \
     
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      Last update: 2006-08-03 11:01    [W:0.026 / U:0.084 seconds]
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