diff options
Diffstat (limited to 'main/qemu/0004-vhost-replace-ffsl-with-ctzl.patch')
| -rw-r--r-- | main/qemu/0004-vhost-replace-ffsl-with-ctzl.patch | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/main/qemu/0004-vhost-replace-ffsl-with-ctzl.patch b/main/qemu/0004-vhost-replace-ffsl-with-ctzl.patch new file mode 100644 index 0000000000..3853dd5a73 --- /dev/null +++ b/main/qemu/0004-vhost-replace-ffsl-with-ctzl.patch @@ -0,0 +1,49 @@ +From f5fba0976a2841e2f4033a01076161ce2ede0477 Mon Sep 17 00:00:00 2001 +From: Natanael Copa <ncopa@alpinelinux.org> +Date: Tue, 29 Apr 2014 14:34:12 +0200 +Subject: [PATCH 4/6] vhost: replace ffsl with ctzl + +Avoid using the GNU extesion ffsl which is not implemented in musl libc. + +The atomic_xchg() means we know that vhost_log_chunk_t will never be +larger than the 'long' type, so ctzl() is always sufficient. + +See also commit fbeadf50 (bitops: unify bitops_ffsl with the one in +host-utils.h, call it bitops_ctzl) on why ctzl should be used instead +of ffsl. + +Signed-off-by: Natanael Copa <ncopa@alpinelinux.org> +--- + hw/virtio/vhost.c | 6 ++---- + 1 file changed, 2 insertions(+), 4 deletions(-) + +diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c +index 9e336ad..f62cfaf 100644 +--- a/hw/virtio/vhost.c ++++ b/hw/virtio/vhost.c +@@ -41,7 +41,6 @@ static void vhost_dev_sync_region(struct vhost_dev *dev, + + for (;from < to; ++from) { + vhost_log_chunk_t log; +- int bit; + /* We first check with non-atomic: much cheaper, + * and we expect non-dirty to be the common case. */ + if (!*from) { +@@ -51,12 +50,11 @@ static void vhost_dev_sync_region(struct vhost_dev *dev, + /* Data must be read atomically. We don't really need barrier semantics + * but it's easier to use atomic_* than roll our own. */ + log = atomic_xchg(from, 0); +- while ((bit = sizeof(log) > sizeof(int) ? +- ffsll(log) : ffs(log))) { ++ while (log) { ++ int bit = ctzl(log); + hwaddr page_addr; + hwaddr section_offset; + hwaddr mr_offset; +- bit -= 1; + page_addr = addr + bit * VHOST_LOG_PAGE; + section_offset = page_addr - section->offset_within_address_space; + mr_offset = section_offset + section->offset_within_region; +-- +1.9.2 + |