tl;dr: Trying to enable BAR on my Haswell Architecture desktop.

This is going to take a lot of text, apologies, but I both knowthat
this task is very unforgiving of mistakes, and i understand just enough
to know that I could turn the computer I've had for... a decade, into a paperweight if I mess up.

My computer: https://support.lenovo.com/us/en/solutions/pd029601-detailed-specifications-for-thinkcentre-m73-small-form-factor

My Motherboard:
https://ctrl-c.club/~singletona082/lenovo-m73sff-mobo.txt

The last bios Lenovo published for this computer: https://support.lenovo.com/us/en/downloads/ds038324-flash-bios-update-thinkcentre-m73-tower-and-small-form-factor-thinkcentre-e73


What I want to do:
Add BAR support to a computer that doesn't have it

'What is BAR?'
https://www.howtogeek.com/819578/what-is-resizable-bar-on-a-gpu/

I am planning on using this guide: https://github.com/xCuri0/ReBarUEFI?tab=readme-ov-file

Right now I'm looking at the following: https://github.com/xCuri0/ReBarUEFI/wiki/Enabling-hidden-4G-decoding
Notes:
At step 6: there were no results for '4g decor', but there were for
'Above 4G'. If I'm reading this right what I'm looking for is
'VarOffset' and if I have the right of what I'm looking for mine is a
value of '0x2CE'

I have not progressed past this step since it involves making changes
to UEFI.

The above is listed as an optional, but nice to have, step since
otherwise BAR allocation is capped at 1G or 512mb.

What I want from the peanut gallary here, especially xwindows if he's
feeling helpful or at least curious on how things explode, is if any of
this is even worth doing outside of a technical level 'huh neat' and
any advice or color commentary about the instructions listed.

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Update:
UEFI change has resulted in no explosions. I have made preparations to
the bios file as per instructions.

However reading further suggests that past enabling 4G via the
bootloader will do the job and a bios reflash is needed only if one is
using Windows. Given Windows 10 support stops this year for non
corporate users ( so much for, 'last version of windows...') and this
computer not meeting the TPM requirements for windows 11? If what i
have done is enough, then I see no reason to go further.

It's still a severe bottleneck even if I upgrade on the cheap to the
fastest xeon that would fit in, and get a nicer card, but this box is
mine and my wants, such as they are, are few enough that just making
things that little bit nicer is enough, until some other tweak presents
itself.

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Andrew Singleton <singletona082@ctrl-c.club> writes:

tl;dr: Trying to enable BAR on my Haswell Architecture desktop.

I know nothing about the subject, but I appreciated your attention in
providing references such as what is BAR. I wish you good luck on the operation and will watch your progress here, trying to understand how
stuff works.
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Update:
While gains on my system seem (relatively) small (in large part due to
my computer's age, bottlenecks from older PCI-E spec, CPU
bottle-necking, alongside a (by modern standards) lower capability GPU
(RX550, i THINK 4gb, could be the 2gb variant,) gains. They are
noticeable just from the initial 'enable 4G block support' step

https://github.com/xCuri0/ReBarUEFI/wiki/Enabling-hidden-4G-decoding

if I am reading the rest correctly, with that enabled the linux kernel
and AMD drivers should handle the rest. As the next steps do not seem
to be needed I am tabling them for the moment while I look into other
potential modifications (and fretting the whole time I'm going to
destroy my computer in the process.)


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