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Re: [RFC] nptl: change default stack guard size of threads
- From: Jeff Law <law at redhat dot com>
- To: Florian Weimer <fweimer at redhat dot com>, James Greenhalgh <james dot greenhalgh at arm dot com>
- Cc: Rich Felker <dalias at libc dot org>, Szabolcs Nagy <Szabolcs dot Nagy at arm dot com>, GNU C Library <libc-alpha at sourceware dot org>, nd <nd at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- Date: Tue, 19 Dec 2017 21:43:45 -0700
- Subject: Re: [RFC] nptl: change default stack guard size of threads
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On 12/19/2017 06:06 AM, Florian Weimer wrote:
> On 12/19/2017 01:34 PM, James Greenhalgh wrote:
>> Option 1: 64k guard pages for LP64 on AArch64.
>> Option 2: 4k guard pages for LP64 for AArch64
>> Our proposal then, having spoken things through with the Arm engineers
>> here, and taken in to consideration the opinions on this thread, is that
>> we move to two "blessed" configurations of the GCC support for AArch64.
> Are there any Arm engineers who prefer Option 2, or is that just there
> to accommodate feedback on libc-alpha?
> My main concern was the variance in configurations with Option 1
> (compared to Option 2). To some extent, the variance with Option 1 is
> temporary. If both Option 1 and 2 are offered, we have permanent
> variance. From my point of view, that's worth that just going with
> Option 1.
> So if this is some sort of consensus proposal, as opposed to actual
> technical requirements which favor Option 2 in some deployments, I think
> that's not a good idea, and we should go with Option 1 instead.
Ideally we set the guard size now and never ever decrease it. I'd
really like to remove the option to make it a compile-time configurable
--param for GCC. ie, it's baked into the port and never changes.