2017-07-05 12:41 GMT-03:00 JF Bastien <[email protected]>: > On Linux you can do the following: > > ((void(*)())0xffff0fa0)(); > > > That address contains a helper which does the “right” barrier, including if > you’re not on an SMP system it’ll do nothing. > > Details: > https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt > That file also lists other Linux helpers. > > I think for ARMv6 it makes sense to use these helpers. AFAIK the mcr barrier > instruction ins’t supported by all ARMv6 CPUs.
Hi JF. Do you mind point me where the mcr isn't supported by all ARMv6 CPU? I've found in ARMv6-M manual (http://infocenter.arm.com/help/topic/com.arm.doc.ddi0419d/DDI0419D_armv6m_arm.pdf) that it doesn't support coprocessor operations, but this architecture is used by microcontroller chips. Regards, Caio. > For ARMv7 and later, DMB ish is the right thing. > > > On Jul 3, 2017, at 17:19, Caio Lima <[email protected]> wrote: > > Hi all. > > I'm working in this patch > (https://bugs.webkit.org/show_bug.cgi?id=172767) and Mark Lam raised > some questions about the data memory barrier (DMB for short) in ARMv6 > using "mcr 15 ...". The point is that we are having divergences in ARM > official reference manual about the semantics of this instruction. We > have it discussed in the bug above and I would like to know if there > is somebody with stronger ARM background that could help us there and > then approve the patch to be committed. > > I thanks in advance and best regards, > Caio Lima. > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev > > _______________________________________________ webkit-dev mailing list [email protected] https://lists.webkit.org/mailman/listinfo/webkit-dev
