On Thu, Dec 20, 2012 at 10:21 AM, H. Peter Anvin <h...@zytor.com> wrote: > On 12/20/2012 09:53 AM, Stefani Seibold wrote: >> >> In a 32 bit kernel a VDSO can mapped on an fix address VDSO_HIGH_BASE >> (kernel parameter vdso32=2 or CONFIG_COMPAT_VDSO), which is 0xffffe000. >> There is no available page BEFORE nor AFTER the page, so it is not >> possible to have VVAR or HPET as a part of that list!!!! >> > > [Cc: Roland, Linus, H.J.] > > The pages before it are safe to use, because they are kernel internal > and hence not ABI (and in fact depend on the kernel configuration > parameters.) So pushing down the start of the fixmap region is not a > problem. This means that to retain this compatibility the existing > entry points need to be at the end, which is more painful than we'd > like, but nevertheless there. > > Do we know what actually used these fixed address, if anything, ever? >
Glibc gets VDSO address from AT_* vector. I think glibc is safe. -- H.J. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
