Hi there,
I'm busy trying to setup the ADC test project written by Pavel@ (repo)(background). In the thread they talk about limiting the accessible RAM from the OS.
I was curious how to do this? Can anyone point me in the correct direction? I'm trying to write to a portion of unused RAM.
Also, what is the significance of 0X1E000000? How was this address chosen? Is there an overall memory map that I can use or resource? I'm guessing this is somewhere near the end of RAM?
Thanks in advance!
(Please excuse my noobness)
Limiting RAM Access
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Re: Limiting RAM Access
Hello,
In Pavel's repo, the two following lines tell Linux not to use the upper 8 MB of RAM between 504 MB and 512 MB (0x1E000000 = 503316480):
https://github.com/pavel-demin/red-pita ... .patch#L41
https://github.com/pavel-demin/red-pita ... .patch#L22
In the ADC project, the RAM writer IP is configured to start writing data in RAM at 504 MB offset:
https://github.com/pavel-demin/red-pita ... n.tcl#L215
The server can then access the data using mmap:
https://github.com/pavel-demin/red-pita ... rver.c#L48
Good luck!
Jean
In Pavel's repo, the two following lines tell Linux not to use the upper 8 MB of RAM between 504 MB and 512 MB (0x1E000000 = 503316480):
https://github.com/pavel-demin/red-pita ... .patch#L41
https://github.com/pavel-demin/red-pita ... .patch#L22
In the ADC project, the RAM writer IP is configured to start writing data in RAM at 504 MB offset:
https://github.com/pavel-demin/red-pita ... n.tcl#L215
The server can then access the data using mmap:
https://github.com/pavel-demin/red-pita ... rver.c#L48
Good luck!
Jean
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- Joined: Mon Nov 07, 2016 1:02 pm
Re: Limiting RAM Access
Thanks for this, Jean.
Do I have to recompile an entire bootable environment for this? I'm not overly familiar with the whole Device Tree /U-Boot stuff.
Is there some simpler way to do this?
-Tighe
Do I have to recompile an entire bootable environment for this? I'm not overly familiar with the whole Device Tree /U-Boot stuff.
Is there some simpler way to do this?
-Tighe
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- Posts: 33
- Joined: Tue Aug 25, 2015 12:17 pm
- Contact:
Re: Limiting RAM Access
Pavel's image has the feature by default.
You don't need to recompile anything.
You don't need to recompile anything.
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