Re: [Xen-devel] [PATCH] libxc: lzma build fix

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Fri, 2011-02-11 at 13:41 +0000, Jan Beulich wrote:
> >>> On 28.01.11 at 19:51, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> wrote:
> > libxc: Do not use host physmem as parameter to lzma decoder
> > 
> > It's not clear why a userspace lzma decode would want to use that
> > particular value, what bearing it has on anything or why it would
> > assume it could use 1/3 of the total RAM in the system (potentially
> > quite a large amount of RAM) as opposed to any other limit number.
> > 
> > Instead, hardcode 32Mby.
> 
> Has anyone of you actually tested this? I don't get lzma to work
> with this set to less than 128Mb, and xz's configure.ac also sort
> of states this to be a minimal requirement for arbitrary input.

I looked quite hard for any documentation on this and couldn't find any,
I could only find examples of people using host physmem like we were or
hardcoding ~30MB.

I should have looked in configure.ac, its obvious really ;-)

Putting aside the fact that 128MB is a quite obscene amount of memory as
a _minimum_ requirement for something like this I guess we should change
the constant.

Ian.

> 
> > This reverts 22830:c80960244942, removes the xc_get_physmem/physmem
> > function entirely, and replaces the expression at the call site with a
> > fixed constant.
> > 
> > Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> > Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
> > Cc: Christoph Egger <Christoph.Egger@xxxxxxx>
> 
> Jan
> 



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