[RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP)
Avi Kivity
avi at redhat.com
Mon Jan 18 12:01:00 UTC 2010
On 01/18/2010 01:44 PM, Peter Zijlstra wrote:
> On Mon, 2010-01-18 at 13:01 +0200, Avi Kivity wrote:
>
>> You've made it clear that you don't like it, but not why.
>>
>> The kernel already manages the user's address space (except for
>> MAP_FIXED which is unreliable unless you've already reserved the address
>> space). I don't see why adding a vma for debugging is so horrible.
>>
> Well, the kernel only does what the user (and loader) tell it through
> mmap().
What I meant was that the kernel chooses the addresses (unless you go
the MAP_FIXED way). From the user's point of view, there is no change
in behaviour: the kernel picks an address. If the constraints have
changed (because we reserve a range), that doesn't affect the user.
> Other than that we never (except this VDSO thing) inject vmas,
> and I see no reason to start doing that now.
>
Maybe you place no value on uprobes. But people who debug userspace
likely will see a reason.
--
error compiling committee.c: too many arguments to function
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