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sh: Add a command line option for disabling I/O trapping.

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This adds a 'noiotrap' kernel command line option to permit disabling of
I/O trapping. This is mostly useful for running on emulators where the
physical device limitations are not an issue.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2009-04-02 12:31:16 +09:00
parent 8dafc34616
commit eeee7853c4
2 changed files with 15 additions and 0 deletions
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2
Documentation/kernel-parameters.txt
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@ -1544,6 +1544,8 @@ and is between 256 and 4096 characters. It is defined in the file
Valid arguments: on, off Valid arguments: on, off
Default: on Default: on
noiotrap [SH] Disables trapped I/O port accesses.
noirqdebug [X86-32] Disables the code which attempts to detect and noirqdebug [X86-32] Disables the code which attempts to detect and
disable unhandled interrupt sources. disable unhandled interrupt sources.

13
arch/sh/kernel/io_trapped.c
View file

@ -14,6 +14,7 @@
#include <linux/bitops.h> #include <linux/bitops.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/init.h>
#include <asm/system.h> #include <asm/system.h>
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
@ -32,6 +33,15 @@ EXPORT_SYMBOL_GPL(trapped_mem);
#endif #endif
static DEFINE_SPINLOCK(trapped_lock); static DEFINE_SPINLOCK(trapped_lock);
static int trapped_io_disable __read_mostly;
static int __init trapped_io_setup(char *__unused)
{
trapped_io_disable = 1;
return 1;
}
__setup("noiotrap", trapped_io_setup);
int register_trapped_io(struct trapped_io *tiop) int register_trapped_io(struct trapped_io *tiop)
{ {
struct resource *res; struct resource *res;
@ -39,6 +49,9 @@ int register_trapped_io(struct trapped_io *tiop)
struct page *pages[TRAPPED_PAGES_MAX]; struct page *pages[TRAPPED_PAGES_MAX];
int k, n; int k, n;
if (unlikely(trapped_io_disable))
return 0;
/* structure must be page aligned */ /* structure must be page aligned */
if ((unsigned long)tiop & (PAGE_SIZE - 1)) if ((unsigned long)tiop & (PAGE_SIZE - 1))
goto bad; goto bad;