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Re: [PATCH] hw/net: move allocation to the heap due to very large stack
From: |
David Gibson |
Subject: |
Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame |
Date: |
Fri, 16 Oct 2020 11:32:18 +1100 |
On Wed, Oct 14, 2020 at 07:15:47AM -0700, Elena Afanasova wrote:
> On Tue, 2020-10-13 at 16:32 +1100, David Gibson wrote:
> > On Mon, Oct 12, 2020 at 03:45:02PM +0200, Paolo Bonzini wrote:
> > > On 12/10/20 12:44, Thomas Huth wrote:
> > > > I think this is one of the tasks from:
> > > >
> > > >
> > > > https://wiki.qemu.org/Contribute/BiteSizedTasks#Compiler-driven_cleanups
> > > >
> > > > It has been added by Paolo in 2016:
> > > >
> > > >
> > > > https://wiki.qemu.org/index.php?title=Contribute/BiteSizedTasks&diff=5368&oldid=5367
> > > >
> > > > ... so maybe Paolo can comment on the size that has been chosen
> > > > here...?
> > >
> > > I used 16K, mostly because it is a nice round number. 8k is too
> > > small
> > > due to PATH_MAX-sized variables. 16k seemed to be plenty and
> > > triggered
> > > in few-enough places that the cleanup is viable.
> >
> > Ok. Why are large stack frames bad in qemu?
> >
>
> I think that the main issue here is alloca() because it can lead to UB.
That's a fair point. I've applied the patch to ppc-for-5.2, with a
tweak to the commit message.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, (continued)
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Philippe Mathieu-Daudé, 2020/10/09
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Greg Kurz, 2020/10/09
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Li Qiang, 2020/10/09
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, David Gibson, 2020/10/10
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Elena Afanasova, 2020/10/10
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, David Gibson, 2020/10/12
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Thomas Huth, 2020/10/12
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Paolo Bonzini, 2020/10/12
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, David Gibson, 2020/10/13
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Elena Afanasova, 2020/10/14
- Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame,
David Gibson <=
Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Li Qiang, 2020/10/10
Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame, Philippe Mathieu-Daudé, 2020/10/12