One more thing. You can get another speed up if you can do burst reads from NOR. This requires using the fifo in the local bus controller. On the ADS5121 board you need a cpld change to increment the address lines. With the cpld as shipped you end up reading bursts that have the first 4 bytes repeated because the address lines do not increment. I don't know if this is feature or bug with the 5121 but I do know you can work around it in the cpld.<br>
<br>With burst access working you should be able to speed up the kernel copy and also the jffs2 mount and filesystem access.<br><br>I also found that coping an uncompressed kernel was faster than decompressing a compressed kernel. But your mileage may vary if you have the data cache on. I found that working around all the problems with turning data cache on were going to take more time than I had.<br>
<br>John<br><br><div class="gmail_quote">On Fri, May 29, 2009 at 2:30 PM, John Rigby <span dir="ltr"><<a href="mailto:jcrigby@gmail.com">jcrigby@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Kenneth,<br><br>I did some fastboot work for 5121 a few months ago. U-boot, kernel and JFFS2 rootfs in NOR. My reset to userland time was 2.0 seconds, where userland was first command executed in first rc.whatever file, so it included the time for /sbin/init to get up and start running the rc scripts.<br>
<br>I did some profiling and noticed that the JFFS2 boot time was a significant hunk (not just the first time but everytime). I ran sumtool on the JFFS2 image and it dropped 600 ms from the boot time so my final time was 1.4 seconds. The sumtool program has been around for a few years but it was news to mean when I found it.<br>
<font color="#888888">
<br>John</font><div><div></div><div class="h5"><br><br><div class="gmail_quote">On Fri, May 29, 2009 at 5:13 AM, Kenneth Johansson <span dir="ltr"><<a href="mailto:kenneth@southpole.se" target="_blank">kenneth@southpole.se</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<a href="http://www.cambridgewireless.co.uk/news/article/default.aspx?objid=36792" target="_blank">http://www.cambridgewireless.co.uk/news/article/default.aspx?objid=36792</a><br>
<br>
Anybody know what they mean by booting here.<br>
<br>
I have started the ads5121 board using u-boot and kernel in NOR flash<br>
and root file system on a compact flash card connected to the IDE<br>
interface in 2.05 second until init is started from the rootfs.<br>
<br>
This was fast enough for what was needed I did not try to optimize<br>
further but since I already was in the domain where changes impacted<br>
only a few milliseconds I have a hard time imagining going down to less<br>
than a second.<br>
<br>
So I guess the only way is to skip u-boot and run linux kernel directly<br>
out of NOR. Anyone know what MontaVista is doing ??<br>
<br>
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