From 461a9afff5e731d6337c0f5b08a1e727ccd57e0a Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Mon, 25 Sep 2006 23:32:25 -0700 Subject: [PATCH] [PATCH] x86: add a bootparameter to reserve high linear address space Add a boot parameter 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 Signed-off-by: Chris Wright Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/kernel-parameters.txt | 5 +++++ arch/i386/kernel/setup.c | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 71d05f48172..766abdab94e 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1363,6 +1363,11 @@ 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 --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c index 060c68004be..16d99444cf6 100644 --- a/arch/i386/kernel/setup.c +++ b/arch/i386/kernel/setup.c @@ -934,6 +934,24 @@ static void __init parse_cmdline_early (char ** cmdline_p) } } +/* + * 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. + */ +static int __init parse_reservetop(char *arg) +{ + unsigned long address; + + if (!arg) + return -EINVAL; + + address = memparse(arg, &arg); + reserve_top_address(address); + return 0; +} +early_param("reservetop", parse_reservetop); + /* * Callback for efi_memory_walk. */ -- 2.39.3