[PATCH 11/14] ARM: v6k: use CPU domain feature if we include support for arch < ARMv6K
tony at atomide.com
Fri Jan 28 11:49:44 EST 2011
* Catalin Marinas <catalin.marinas at arm.com> [110128 07:11]:
> On Fri, 2011-01-28 at 13:21 +0000, Russell King - ARM Linux wrote:
> > On Fri, Jan 28, 2011 at 12:25:18PM +0000, Catalin Marinas wrote:
> > > With your latest patches, do we use the TLS emulation on ARMv7 (UP) if
> > > v6 is compiled in? If that's the case, we may have a problem - I talked
> > > to the toolchain guys and it looks like code optimised for ARMv7 reads
> > > the TLS register directly without going through the kuser helper. So you
> > > may have people taking an Ubuntu filesystem (v7 only) and a pre-built
> > > OMAP image with TLS emulation even on Cortex-A8 and things won't work as
> > > expected.
> > You're really making a mountain out of TLS.
> Not really, just asking for clarification as I haven't checked all your
> patches recently.
> > If we have a v6+v6k+v7 kernel, then the way the kernel TLS code is built,
> > we will use the TLS register if that's available on the hardware. If it
> > isn't, we will write the TLS value directly to virtual 0xffff0ffc.
> > So, a kernel built for v6+v6k+v7, when run on v7, will set the hardware
> > TLS register, and your v7 optimized binaries which access the TLS register
> > directly will work. Same for v6k.
Yes AFAIK we sorted out the TLS issue already a while back for v6+v6k+v7.
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