Re: [PATCH v2] x86: Remove compat vdso support

[Andy Lutomirski]

On Wed, Mar 12, 2014 at 4:06 PM, H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> wrote:
> On 03/12/2014 02:49 PM, Andy Lutomirski wrote:
>> On Wed, Mar 12, 2014 at 2:46 PM, Linus Torvalds
>> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>>> On Wed, Mar 12, 2014 at 2:37 PM, H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> wrote:
>>>>
>>>> How would that deal with the legacy vsyscall case for x86-64?  Just rely
>>>> on the "legacy vsyscall emulation" (which seems to have its own class of
>>>> problems...)?
>>>
>>> It does?
>>>
>>> We *default* to emulation, and have for over two years now (since
>>> v3.4).  If there are problems with it, we need to fix those.
>>
>> Even in the non-default "vsyscall=native" case, the vsyscall pages
>> just contains syscalls.  It does not need to access the vvar page, the
>> hpet, or anything else that the vdso uses.
>>
>
> Ah, right.  I let that detail slip the mind.
>
> I do hear vsyscall=native still being used as a workaround for problems,
> but yes, just making it call the kernel is fine, of course.

Next time you hear that, can you let me know?  I haven't heard of any
issues since 3.4 IIRC.

--Andy

>
> So yes, this does make it all better.
>
>         -hpa
>
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/