svn_rev_636

1 files changed, 20 insertions, 5 deletions

diff --git a/Documentation/porting.txt b/Documentation/porting.txt
index 167a11c4b2..adbbb6ce5b 100644
--- a/Documentation/porting.txt
+++ b/Documentation/porting.txt
@@ -73,6 +73,17 @@ console_initcall(scb9328_console_init);
     EEPROM just return -1. set_mac_address() shall set the MAC address in
     the device. All magic previously done with getenv/setenv(ethaddr) must be
     removed.
+    During startup U-Boot calls get_mac_address() to see if an EEPROM is
+    connected. If so, it calls set_mac_address() with this address. This
+    is done even if networking is not used during startup. This makes sure
+    that the MAC address is set in the device and Linux can pick it up later.
+  - There is now (the beginning of) generic phy support. When porting drivers
+    it is recommended to use it. The phy support currently only starts generic
+    autonegotiation, so if you have some fancy things to do (or have gigabit
+    ethernet) you'll have to extend the phy layer first. Although this is
+    extra work, it will pay off some day, as phy support is a great source
+    of duplicated code. see drivers/net/dm9000.c or drivers/net/fec_mpc5200.c
+    for examples.
 
 - Add a clocksource for your system. PowerPCs have a generic decrementer
   counter, so if you have a PowerPC aou have nothing to do here. on ARM
@@ -97,10 +108,14 @@ calc_source:
 	subi    r4, r4, 0x100
 
   (I'm almost sure that PowerPC has a dedicated instruction for this, un-
-  fortunately I know next to nothing of PowerPC assembler)
+  fortunately I know next to nothing of PowerPC assembler, so if you have
+  a better way to archieve this, please write to the list)
 
-  U-Boot runs now from the address it was linked to, so on PowerPC you have
-  to adjust TEXT_BASE to be in RAM. This makes the various fixup functions
-  unnecessary. It also simplifies debugging because you will see the
-  correct addresses in the objdump.
+  On PowerPC U-Boot now runs at the address it was linked to, so you have
+  to adjust TEXT_BASE to be in RAM. This makes the various fixup relocation
+  functions unnecessary. On PowerPC the removal of -fPIC saves around 10% of
+  binary space. It also simplifies debugging because you will see the correct
+  addresses in the objdump without doing offset calculation.
 
+- On arm most of the duplicate code under cpu/arm* is already merged into
+  arch/arm/cpu. the start.S files are missing though.