Re: [Qemu-devel] [PATCH] sparc: Make sure we mmap at SHMLBA alignment

[Richard Henderson <richard.henderson@linaro.org>]

On 12/08/2017 08:57 AM, Peter Maydell wrote:
> SPARC Linux has an oddity that it insists that mmap()
> of MAP_FIXED memory must be at an alignment defined by
> SHMLBA, which is more aligned than the page size
> (typically, SHMLBA alignment is to 16K, and pages are 8K).
> This is a relic of ancient hardware that had cache
> aliasing constraints, but even on modern hardware the
> kernel still insists on the alignment.
> 
> To ensure that we get mmap() alignment sufficient to
> make the kernel happy, change QEMU_VMALLOC_ALIGN,
> qemu_fd_getpagesize() and qemu_mempath_getpagesize()
> to use the maximum of getpagesize() and SHMLBA.
> 
> In particular, this allows 'make check' to pass on Sparc:
> we were previously failing the ivshmem tests.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~