Why is swap_bytes right solution? It feels like if anything we just need to remove le_to_cpu32
On Tue, Dec 5, 2017, 13:23 <dieg...@linux.vnet.ibm.com> wrote: > From: Masahiro Matsuya <mmats...@redhat.com> > > The netmask configured in firmware is not respected on ppc64 (big endian). > When 255.255.252.0 is set as netmask in firmware, the following is the > value of bootpath string in grub_ieee1275_parse_bootpath(). > > /vdevice/l-lan@30000002 > :speed=auto,duplex=auto,192.168.88.10,,192.168.89.113,192.168.88.1,5,5,255.255.252.0,512 > > The netmask in this bootpath is no problem, since it's a value specified > in firmware. But, > The value of 'subnet_mask.ipv4' was set with 0xfffffc00, and __builtin_ctz > (~grub_le_to_cpu32 (subnet_mask.ipv4)) returned 16 (not 22). > As a result, 16 was used for netmask wrongly. > > 1111 1111 1111 1111 1111 1100 0000 0000 # subnet_mask.ipv4 (=0xfffffc00) > 0000 0000 1111 1100 1111 1111 1111 1111 # grub_le_to_cpu32 > (subnet_mask.ipv4) > 1111 1111 0000 0011 0000 0000 0000 0000 # ~grub_le_to_cpu32 > (subnet_mask.ipv4) > > And, the count of zero with __builtin_ctz can be 16. > This patch changes it as below. > > 1111 1111 1111 1111 1111 1100 0000 0000 # subnet_mask.ipv4 (=0xfffffc00) > 0000 0000 1111 1100 1111 1111 1111 1111 # grub_le_to_cpu32 > (subnet_mask.ipv4) > 1111 1111 1111 1111 1111 1100 0000 0000 # > grub_swap_bytes32(grub_le_to_cpu32 (subnet_mask.ipv4)) > 0000 0000 0000 0000 0000 0011 1111 1111 # > ~grub_swap_bytes32(grub_le_to_cpu32 (subnet_mask.ipv4)) > > The count of zero with __builtin_clz can be 22. (clz counts the number of > one bits preceding the most significant zero bit) > --- > grub-core/net/drivers/ieee1275/ofnet.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/grub-core/net/drivers/ieee1275/ofnet.c > b/grub-core/net/drivers/ieee1275/ofnet.c > index 002446be1..3df75357a 100644 > --- a/grub-core/net/drivers/ieee1275/ofnet.c > +++ b/grub-core/net/drivers/ieee1275/ofnet.c > @@ -220,8 +220,7 @@ grub_ieee1275_parse_bootpath (const char *devpath, > char *bootpath, > flags); > inter->vlantag = vlantag; > grub_net_add_ipv4_local (inter, > - __builtin_ctz (~grub_le_to_cpu32 > (subnet_mask.ipv4))); > - > + __builtin_clz > (~grub_swap_bytes32(grub_le_to_cpu32 (subnet_mask.ipv4)))); > } > > if (gateway_addr.ipv4 != 0) > -- > 2.13.5 > > > _______________________________________________ > Bug-grub mailing list > Bug-grub@gnu.org > https://lists.gnu.org/mailman/listinfo/bug-grub >
_______________________________________________ Bug-grub mailing list Bug-grub@gnu.org https://lists.gnu.org/mailman/listinfo/bug-grub
