[HN Gopher] UEFI-Only Support for AMD Radeon RX 9000 Series Grap...
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       UEFI-Only Support for AMD Radeon RX 9000 Series Graphics and Later
        
       Author : doener
       Score  : 17 points
       Date   : 2025-03-04 14:09 UTC (3 days ago)
        
 (HTM) web link (www.amd.com)
 (TXT) w3m dump (www.amd.com)
        
       | teach wrote:
       | Honest question: who is still using BIOS (or I guess CSM mode)
       | and why?
       | 
       | I was a BIOS holdout, and even I switched to pure-UEFI _years_
       | ago.
        
         | Delomomonl wrote:
         | I booted my arch Linux Kernel straight from UEFI 9 years ago :)
        
         | ChocolateGod wrote:
         | I still see it used commonly for VMs.
        
         | Paianni wrote:
         | All of my PCs except an old MacBook Pro have a BIOS, not UEFI.
         | 
         | Two are from 2010, one from 2008, one from 1996.
        
           | doener wrote:
           | Do you use a modern graphics card in any of them?
        
         | HankB99 wrote:
         | I have an old server motherboard that does not support UEFI.
         | Otherwise it still runs fine.
         | 
         | I came here to ask why it matters to the GPU how the host
         | boots. Does it need to load some drivers or firmware before the
         | host OS? The only thing I found in the article was "... may
         | lose access to important and necessary features of your
         | motherboard,"
        
           | wmf wrote:
           | Resizable BAR (which doesn't exist on old pre-UEFI hardware
           | anyway).
        
         | diego_sandoval wrote:
         | I used to use CSM mode because I didn't understand how UEFI
         | worked, specifically the Boot Manager.
         | 
         | My Boot Manager always ended up full of old entries of OSes
         | that I had already deleted, and it caused some issues. This was
         | not a problem in compatibility mode.
         | 
         | But then I read an article [1] and learned how to manage the
         | Boot Manager.
         | 
         | Then I made a video [2] summarizing what I learned from the
         | article.
         | 
         | But to this day, I defend the point that UEFI is not a drop-in
         | replacement for BIOS, because if you install and delete OSs
         | frequently, you need to know how to manage the Boot Manager to
         | avoid ending up with a mess.
         | 
         | [1] https://www.happyassassin.net/posts/2014/01/25/uefi-boot-
         | how...
         | 
         | [2] https://www.youtube.com/watch?v=-V3VhP-MUwE
        
           | hnuser123456 wrote:
           | Nice, thank you! I stopped experimenting with OSes right
           | around the time UEFI took over so I never would've known.
        
       | jauntywundrkind wrote:
       | Note Toms Hardware on this:
       | 
       | > _Let 's make one thing clear, this does not mean that RDNA 4
       | (and future) GPUs will not boot on older systems. AMD simply does
       | not guarantee an optimal experience, stating that your GPU could
       | be missing out on necessary features such as Smart Access
       | Memory._
       | 
       | https://www.tomshardware.com/pc-components/gpus/amds-new-rx-...
        
       | jauntywundrkind wrote:
       | Note Toms Hardware on this:
       | 
       | > _Let 's make one thing clear, this does not mean that RDNA 4
       | (and future) GPUs will not boot on older systems. AMD simply does
       | not guarantee an optimal experience, stating that your GPU could
       | be missing out on necessary features such as Smart Access
       | Memory._
       | 
       | And possibly compatibility or crashing issues, they continue on
       | to say.
       | 
       | https://www.tomshardware.com/pc-components/gpus/amds-new-rx-...
        
       | kaszanka wrote:
       | BAR resizing (which is all that Smart Access Memory means, as far
       | as I can tell) is just done by the kernel writing some value to
       | the right field in PCI configuration space, why would it require
       | firmware support (and if so, why would CSM preclude that
       | support)?
        
         | wmf wrote:
         | There are a lot of features that Intel has decided are
         | "supposed" to be enabled by firmware and Windows just goes
         | along with that. AMD copies Intel for compatibility of course.
        
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       (page generated 2025-03-07 23:00 UTC)