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paravirt: helper to disable all IO space

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In a virtual environment, device drivers such as legacy IDE will waste
quite a lot of time probing for their devices which will never appear.
This helper function allows a paravirt implementation to lay claim to
the whole iomem and ioport space, thereby disabling all device drivers
trying to claim IO resources.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Jeremy Fitzhardinge 2007-07-17 18:37:04 -07:00 committed by Jeremy Fitzhardinge
parent 5f4352fbff
commit d572929cdd
2 changed files with 36 additions and 0 deletions
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35
arch/i386/kernel/paravirt.c
View file

@ -228,6 +228,41 @@ static int __init print_banner(void)
}
core_initcall(print_banner);
static struct resource reserve_ioports = {
.start = 0,
.end = IO_SPACE_LIMIT,
.name = "paravirt-ioport",
.flags = IORESOURCE_IO | IORESOURCE_BUSY,
};
static struct resource reserve_iomem = {
.start = 0,
.end = -1,
.name = "paravirt-iomem",
.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
};
/*
* Reserve the whole legacy IO space to prevent any legacy drivers
* from wasting time probing for their hardware. This is a fairly
* brute-force approach to disabling all non-virtual drivers.
*
* Note that this must be called very early to have any effect.
*/
int paravirt_disable_iospace(void)
{
int ret;
ret = request_resource(&ioport_resource, &reserve_ioports);
if (ret == 0) {
ret = request_resource(&iomem_resource, &reserve_iomem);
if (ret)
release_resource(&reserve_ioports);
}
return ret;
}
struct paravirt_ops paravirt_ops = {
.name = "bare hardware",
.paravirt_enabled = 0,

1
include/asm-i386/paravirt.h
View file

@ -262,6 +262,7 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len)
unsigned paravirt_patch_insns(void *site, unsigned len,
const char *start, const char *end);
int paravirt_disable_iospace(void);
/*
* This generates an indirect call based on the operation type number.