diff options
author | Rusty Russell <rusty@rustcorp.com.au> | 2007-07-26 10:41:05 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-26 11:35:17 -0700 |
commit | f56a384e98aa81065038c4e16f39ed989ccae687 (patch) | |
tree | 923bcaabd76a88351fe5e61370143350747a90c4 /drivers/lguest/interrupts_and_traps.c | |
parent | f8f0fdcd40449d318f8dc30c1b361b0b7f54134a (diff) | |
download | kernel_samsung_tuna-f56a384e98aa81065038c4e16f39ed989ccae687.zip kernel_samsung_tuna-f56a384e98aa81065038c4e16f39ed989ccae687.tar.gz kernel_samsung_tuna-f56a384e98aa81065038c4e16f39ed989ccae687.tar.bz2 |
lguest: documentation VII: FIXMEs
Documentation: The FIXMEs
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/lguest/interrupts_and_traps.c')
-rw-r--r-- | drivers/lguest/interrupts_and_traps.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c index 3d98303..bd0091b 100644 --- a/drivers/lguest/interrupts_and_traps.c +++ b/drivers/lguest/interrupts_and_traps.c @@ -231,6 +231,20 @@ static int direct_trap(const struct lguest *lg, * go direct, of course 8) */ return idt_type(trap->a, trap->b) == 0xF; } +/*:*/ + +/*M:005 The Guest has the ability to turn its interrupt gates into trap gates, + * if it is careful. The Host will let trap gates can go directly to the + * Guest, but the Guest needs the interrupts atomically disabled for an + * interrupt gate. It can do this by pointing the trap gate at instructions + * within noirq_start and noirq_end, where it can safely disable interrupts. */ + +/*M:006 The Guests do not use the sysenter (fast system call) instruction, + * because it's hardcoded to enter privilege level 0 and so can't go direct. + * It's about twice as fast as the older "int 0x80" system call, so it might + * still be worthwhile to handle it in the Switcher and lcall down to the + * Guest. The sysenter semantics are hairy tho: search for that keyword in + * entry.S :*/ /*H:260 When we make traps go directly into the Guest, we need to make sure * the kernel stack is valid (ie. mapped in the page tables). Otherwise, the |