Home ›

Porting LinuxBIOS to the AMD SC520: A Follow-up Report

Jul 19, 2005  By Ronald Minnich
 in
Getting the board Flashed led to some interesting detective work for the LANL team.
______________________

Comments

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

MMCR can be moved...

AndrewD's picture
Submitted by AndrewD (not verified) on Wed, 07/20/2005 - 19:16.

Quote:
"Probably the single biggest problem is the location of the configuration registers, placed right in the middle of the top 2MB of memory"

You can map the MMCR to any 4k offset in the lower 1G by writing to the CBAR register. 0xFFFEF000 is just the default location, so I would not see that as a flaw.

I ended up using rolo instead of Linuxbios on a SC520 based product I designed a few years ago. U-boot is another very powerful option, but they are both more targeted to embedded products.

MMCR can be moved ... but not removed.

Stefan Reinauer's picture
Submitted by Stefan Reinauer (not verified) on Fri, 03/17/2006 - 13:07.

The problem in this case is that even if you "move" the MMCR, it is still sitting at its old position 0xFFFEF000, in addition to the new one.

Code sample

Craig Ringer's picture
Submitted by Craig Ringer (not verified) on Sun, 07/24/2005 - 08:08.

The code snippet is broken - presumably due to mangling by a CMS. Given the extreme difficulty I'm having in getting this godawful commenting system to not mangle these code snippets, that's my working theory. LJ staff, please fix your CMS so it doesn's strip spaces in >code<>/code< blocks! I had to use   in a >code<>/code<block, which is (a) gross and (b) should probably not be interpreted as an entity, but rather as a literal.

In addition to the total loss of indenting, I found two other problems. First:


bios = mmap(0, size, PROT_READ, MAP_SHARED, fd_mem,
off_t) (0xffffffff - size + 1));

looks like it should be:


bios = mmap(0, size, PROT_READ, MAP_SHARED, fd_mem,
           (off_t)(0xffffffff - size + 1) );

and:


#include #
include

should evidently be:


#include
#include

With those changes it builds OK here. The dump doesn't look too interesting on this system - probably not a flash image, anyway - but it's an AMD64 box so it's quite likely the flash is mapped to somewhere different. Any idea what address it might be at?

White Paper
More Resources
Fabric-Based Computing Enables Optimized Hyperscale Data Centers

Today’s modular x86 servers are compute-centric, designed as a least common denominator to support a wide range of IT workloads. Those generic, virtualized IT workloads have much different resource optimization requirements than hyperscale and cloud applications. They have resulted in a “one size fits all” enterprise IT architecture that is not optimized for a specific set of IT workloads, and especially not emerging hyperscale workloads, such as web applications, big data, and object storage. In this report, you will learn how shifting the focus from traditional compute-centric IT architectures to an innovative disaggregated fabric-based architecture can optimize and scale your data center.

Learn More

Sponsored by AMD

White Paper
More Resources
Red Hat White Paper: Using an Open Source Framework to Catch the Bad Guy

Built-in forensics, incident response, and security with Red Hat Enterprise Linux 6

Every security policy provides guidance and requirements for ensuring adequate protection of information and data, as well as high-level technical and administrative security requirements for a system in a given environment. Traditionally, providing security for a system focuses on the confidentiality of the information on it. However, protecting the data integrity and system and data availability is just as important. For example, when processing United States intelligence information, there are three attributes that require protection: confidentiality, integrity, and availability.

Learn more about catching the bad guy in this free white paper.

Learn More

Sponsored by DLT Solutions