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
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