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sparc: Make sure we mmap at SHMLBA alignment

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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.

Backports commit 57d1f6d7ce23e79a8ebe4a57bd2363b269b4664b from qemu
This commit is contained in:
Peter Maydell 2018-03-05 14:09:52 -05:00 committed by Lioncash
parent 60136b485c
commit b54cfecf1e
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1 changed files with 3 additions and 0 deletions
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3
qemu/util/oslib-posix.c
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@ -35,6 +35,9 @@
#elif defined(__linux__) && defined(__s390x__)
/* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
# define QEMU_VMALLOC_ALIGN (256 * 4096)
#elif defined(__linux__) && defined(__sparc__)
#include <sys/shm.h>
# define QEMU_VMALLOC_ALIGN MAX(getpagesize(), SHMLBA)
#else
# define QEMU_VMALLOC_ALIGN getpagesize()
#endif