Hello, I agree with just removing le_to_cpu32. I wrote the patch one year ago, and I don't remember the intent. But maybe, I had some wrong assumption at that time. For now, I think it looks better to remove le_to_cpu32 without swap_bytes for both LE and BE environment.
Thanks, Masahiro Matsuya On Wed, Dec 6, 2017 at 1:12 AM, diegodo <dieg...@linux.vnet.ibm.com> wrote: > Sending the thread to the author (sorry, I missed his email). > > On 2017-12-05 11:26, Vladimir 'phcoder' Serbinenko wrote: >> >> 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 [1] >> >> >> >> Links: >> ------ >> [1] https://lists.gnu.org/mailman/listinfo/bug-grub >> >> _______________________________________________ >> 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