[HN Gopher] Access BMC UART on Supermicro X11SSH
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       Access BMC UART on Supermicro X11SSH
        
       Author : pietrushnic
       Score  : 51 points
       Date   : 2025-06-26 14:40 UTC (8 hours ago)
        
 (HTM) web link (github.com)
 (TXT) w3m dump (github.com)
        
       | treve wrote:
       | This is very interesting, but I'm a little lost. UART is serial.
       | Are they trying to get a serial terminal set up with some chip on
       | this motherboard? Wat does it let them do?
        
         | duskwuff wrote:
         | "X11SSH" is a Supermicro motherboard [1] with a (fairly common)
         | Aspeed BMC implementing IPMI. (It has nothing to do with X11 or
         | SSH - the name is an unfortunate coincidence.) The UART that is
         | being accessed here is a debug UART for the BMC, which _also_
         | runs Linux.
         | 
         | [1]:
         | https://www.supermicro.com/en/products/motherboard/x11ssh-f
        
           | johng wrote:
           | Great explanation.
        
       | KenoFischer wrote:
       | Funny to see this come back and see my write-up linked. I did
       | this 8 years ago and think I was the first on this particular
       | board (although others had done similar on other boards). I still
       | have a pile of them sitting on my desk because I accidentally
       | kept bricking them by being ... not careful. That said, even at
       | the time this board was already old, so I guess it's positively
       | prehistoric at this point. I eventually stopped working on this
       | because I thought that others were making sufficient progress. It
       | hasn't really fully materialized yet, but between openbmc,
       | opensil, DC-SCM and the work the oxide folks are doing, I'm still
       | hopeful that we'll get out of server firmware hell eventually.
        
         | duskwuff wrote:
         | Out of curiosity: how "bricked" are these boards? Is there
         | irreversible hardware damage (and, if so, how?), or has some
         | firmware just gotten overwritten?
        
           | KenoFischer wrote:
           | One of them I managed to fry the pcie root complex somehow,
           | not sure exactly how. One I damaged the traces to the BMC SPI
           | flash. Two others I think just have bricked firmware, but
           | it's been years, so I don't remember for sure.
        
       | sneak wrote:
       | What is the benefit of this?
        
         | pietrushnic wrote:
         | Possibility of runtime exploration of the system which may help
         | in OpenBMC port.
        
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       (page generated 2025-06-26 23:01 UTC)