Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP)

From: Avi Kivity
Date: Mon Jan 18 2010 - 07:01:54 EST

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

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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