* [Qemu-devel] Unposted reserved_va patch
@ 2010-06-02 17:20 Richard Henderson
2010-06-03 4:54 ` [Qemu-devel] " Paul Brook
0 siblings, 1 reply; 3+ messages in thread
From: Richard Henderson @ 2010-06-02 17:20 UTC (permalink / raw)
To: Paul Brook; +Cc: qemu-devel
Re: 68a1c816868b3e35a1da698af412b29e61b1948a
In general, I like the idea (especially since I've proposed it before. ;-)
However:
+ if (have_guest_base) {
+ flags |= MAP_FIXED;
+ }
I think this is broken. If the user specifies -G n -R m they're hoping
or guessing that the range [n,n+m) is free. What they're not expecting
is for the qemu application or any of the required shared libraries to
get forcibly unmapped.
I think instead you should simply adjust the error reporting after the
mmap attempt without MAP_FIXED.
r~
^ permalink raw reply [flat|nested] 3+ messages in thread* [Qemu-devel] Re: Unposted reserved_va patch
2010-06-02 17:20 [Qemu-devel] Unposted reserved_va patch Richard Henderson
@ 2010-06-03 4:54 ` Paul Brook
2010-06-03 14:05 ` Richard Henderson
0 siblings, 1 reply; 3+ messages in thread
From: Paul Brook @ 2010-06-03 4:54 UTC (permalink / raw)
To: Richard Henderson; +Cc: qemu-devel
> Re: 68a1c816868b3e35a1da698af412b29e61b1948a
>
> In general, I like the idea (especially since I've proposed it before. ;-)
>
> However:
>
> + if (have_guest_base) {
> + flags |= MAP_FIXED;
> + }
>
> I think this is broken. If the user specifies -G n -R m they're hoping
> or guessing that the range [n,n+m) is free. What they're not expecting
> is for the qemu application or any of the required shared libraries to
> get forcibly unmapped.
>
> I think instead you should simply adjust the error reporting after the
> mmap attempt without MAP_FIXED.
Hmm, maybe. My reasoning was that this is consistent with the current behavior
of the ELF loader. If you specify -G then the target application will be
splatted at that address, regardless of whether it's already used by the host.
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread* [Qemu-devel] Re: Unposted reserved_va patch
2010-06-03 4:54 ` [Qemu-devel] " Paul Brook
@ 2010-06-03 14:05 ` Richard Henderson
0 siblings, 0 replies; 3+ messages in thread
From: Richard Henderson @ 2010-06-03 14:05 UTC (permalink / raw)
To: Paul Brook; +Cc: qemu-devel
On 06/02/2010 09:54 PM, Paul Brook wrote:
> Hmm, maybe. My reasoning was that this is consistent with the current behavior
> of the ELF loader. If you specify -G then the target application will be
> splatted at that address, regardless of whether it's already used by the host.
Well, sort-of. Before you removed PAGE_RESERVED we'd yield a
very cryptic error message about mmap failed and exit.
r~
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2010-06-03 14:05 UTC | newest]
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2010-06-02 17:20 [Qemu-devel] Unposted reserved_va patch Richard Henderson
2010-06-03 4:54 ` [Qemu-devel] " Paul Brook
2010-06-03 14:05 ` Richard Henderson
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