Re: [U-Boot] [PATCH v4 2/3] net: add helper to generate random mac address

[Mike Frysinger]

On Friday 11 May 2012 15:21:19 Wolfgang Denk wrote:
> Michael Walle wrote:
> > Add new function eth_random_enetaddr() to generate a locally administered
> > ethernet address.
> > 
> > Signed-off-by: Michael Walle 
> > ---
> > 
> >  include/net.h |   15 +++
> >  net/eth.c |   20 
> >  2 files changed, 35 insertions(+), 0 deletions(-)
> 
> Please make this code configurable.  I don't want to bloat code size
> for all boards when only one or two will ever use this feature.

it would be nice if we could standardize gc-sections across the board
-mike


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Re: [U-Boot] [PATCH v4 2/3] net: add helper to generate random mac address

[Wolfgang Denk]

Dear Michael Walle,

In message <1336671134-16342-3-git-send-email-mich...@walle.cc> you wrote:
> Add new function eth_random_enetaddr() to generate a locally administered
> ethernet address.
> 
> Signed-off-by: Michael Walle 
> ---
>  include/net.h |   15 +++
>  net/eth.c |   20 
>  2 files changed, 35 insertions(+), 0 deletions(-)

Please make this code configurable.  I don't want to bloat code size
for all boards when only one or two will ever use this feature.

Best regards,

Wolfgang Denk

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[U-Boot] [PATCH v4 2/3] net: add helper to generate random mac address

[Michael Walle]

Add new function eth_random_enetaddr() to generate a locally administered
ethernet address.

Signed-off-by: Michael Walle 
---
 include/net.h |   15 +++
 net/eth.c |   20 
 2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/include/net.h b/include/net.h
index ee11f82..0da5679 100644
--- a/include/net.h
+++ b/include/net.h
@@ -118,6 +118,21 @@ extern int eth_setenv_enetaddr(char *name, const uchar 
*enetaddr);
 extern int eth_getenv_enetaddr_by_index(const char *base_name, int index,
uchar *enetaddr);
 
+/*
+ * The u-boot policy does not allow hardcoded ethernet addresses. Under the
+ * following circumstances a random generated address is allowed:
+ *  - in emergency cases, where you need a working network connection to set
+ *the ethernet address.
+ *Eg. you want a rescue boot and don't have a serial port to access the
+ *CLI to set environment variables.
+ *
+ * In these cases, we generate a random locally administered ethernet address.
+ *
+ * Args:
+ *  enetaddr - returns 6 byte hardware address
+ */
+extern void eth_random_enetaddr(uchar *enetaddr);
+
 extern int usb_eth_initialize(bd_t *bi);
 extern int eth_init(bd_t *bis);/* Initialize the 
device */
 extern int eth_send(volatile void *packet, int length);   /* Send a 
packet */
diff --git a/net/eth.c b/net/eth.c
index 3eeb908..3623825 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -70,6 +70,26 @@ static int eth_mac_skip(int index)
return ((skip_state = getenv(enetvar)) != NULL);
 }
 
+void eth_random_enetaddr(uchar *enetaddr)
+{
+   uint32_t rval;
+
+   srand(get_timer(0));
+
+   rval = rand();
+   enetaddr[0] = rval & 0xff;
+   enetaddr[1] = (rval >> 8) & 0xff;
+   enetaddr[2] = (rval >> 16) & 0xff;
+
+   rval = rand();
+   enetaddr[3] = rval & 0xff;
+   enetaddr[4] = (rval >> 8) & 0xff;
+   enetaddr[5] = (rval >> 16) & 0xff;
+
+   /* make sure it's local and unicast */
+   enetaddr[0] = (enetaddr[0] | 0x02) & ~0x01;
+}
+
 /*
  * CPU and board-specific Ethernet initializations.  Aliased function
  * signals caller to move on
-- 
1.7.2.5

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