increase lowmem value for ppc
Is there a way to increase the lowmem value for ppc. The MAX_LOW_MEM is defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.
Thanks
Ruksen INANIR ha scritto:
Quoted 11 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.Thanks
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With 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
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Marco Stornelli Embedded Software Engineer CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni http://www.coritel.it [email protected] +39 06 72582838
Marco Stornelli ha scritto:
Quoted 6 lines
Ruksen INANIR ha scritto:
Quoted 5 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.
Quoted 8 lines
Quoted 6 lines
Thanks
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https://ozlabs.org/mailman/listinfo/linuxppc-embeddedWith 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
Only an additional comment: I meant with the address splitting 3G/1G. To map more than 1GB, you have to change the splitting 2G/2G for example.
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Marco Stornelli Embedded Software Engineer CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni http://www.coritel.it [email protected] +39 06 72582838
Is there any side effects of changing the address splitting? What should i change for 2G/2G splitting? should i shift the kernel start? Thanks
Quoted 17 lines · Marco Stornelli
Marco Stornelli ha scritto:
Quoted 6 lines
Ruksen INANIR ha scritto:
Quoted 5 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.Quoted 8 lines
Quoted 6 lines
Thanks
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Linuxppc-embedded mailing list
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https://ozlabs.org/mailman/listinfo/linuxppc-embeddedWith 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
Only an additional comment: I meant with the address splitting 3G/1G. To map more than 1GB, you have to change the splitting 2G/2G for example.
Ruksen INANIR ha scritto:
Quoted 2 lines
Is there any side effects of changing the address splitting?
Yes, in this way the application address space is smaller than normal. Some big applications (for example same dbms) might not work. Usually with 2G/2G most of the applications work well.
Quoted 3 lines
What should i change for 2G/2G splitting? should i shift the kernel start? Thanks
Yes in advanced options of the kernel menu, but sometimes it's not easy.
Sometimes ago I had to do the same thing but I have to change the
kernel code because some operations were hard-coded. Be careful because it's not an easy operation. However I'd suggest you to use the highmem, the memory performance are worse than direct memory mapping, but usually it's not a problem because the overhead is low.
Quoted 25 lines
Quoted 13 lines · Marco Stornelli
Marco Stornelli ha scritto:
Quoted 12 lines
Ruksen INANIR ha scritto:
Quoted 11 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.Thanks
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https://ozlabs.org/mailman/listinfo/linuxppc-embeddedQuoted 4 lines
Quoted 2 lines
With 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
Only an additional comment: I meant with the address splitting 3G/1G. To map more than 1GB, you have to change the splitting 2G/2G for example.
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Marco Stornelli Embedded Software Engineer CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni http://www.coritel.it [email protected] +39 06 72582838
Thanks for your comments.
I tried the highmem option but one of the device drivers does not support highmem, so it did not work.
the only choice for me is to increase the lowmem to 1520 MB. the maximum lowmem value i reached succesfully is 1503 MB. but any value more than 1503 results kernel not able to load kernel modules. Upgrading to a 2.6.x kernel may solve the problem, but it needs a lot of effort. Does 2.6.x kernel support 2G physical memory?
Quoted 38 lines · Marco Stornelli
Ruksen INANIR ha scritto:
Quoted 2 lines
Is there any side effects of changing the address splitting?
Yes, in this way the application address space is smaller than normal. Some big applications (for example same dbms) might not work. Usually with 2G/2G most of the applications work well.
Quoted 3 lines
What should i change for 2G/2G splitting? should i shift the kernel start? Thanks
Yes in advanced options of the kernel menu, but sometimes it's not easy. Sometimes ago I had to do the same thing but I have to change the kernel code because some operations were hard-coded. Be careful because it's not an easy operation. However I'd suggest you to use the highmem, the memory performance are worse than direct memory mapping, but usually it's not a problem because the overhead is low.
Quoted 25 lines
Quoted 13 lines · Marco Stornelli
Marco Stornelli ha scritto:
Quoted 12 lines
Ruksen INANIR ha scritto:
Quoted 11 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.Thanks
_______________________________________________
Linuxppc-embedded mailing list
[email protected]
https://ozlabs.org/mailman/listinfo/linuxppc-embeddedQuoted 4 lines
Quoted 2 lines
With 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
Only an additional comment: I meant with the address splitting 3G/1G. To map more than 1GB, you have to change the splitting 2G/2G for example.
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Ruksen INANIR ha scritto:
Quoted 3 lines
Thanks for your comments.
I tried the highmem option but one of the device drivers does not support highmem, so it did not work.
Strange....you can try to look at it, it could be only some GFP flag.
Quoted 1 line
the only choice for me is to increase the lowmem to 1520 MB. the maximum lowmem value i reached succesfully is 1503 MB. but any value more than 1503 results kernel not able to load kernel modules.
Mmmm....have you tried a stress test? It sounds like a bit strange that the kernel works well with this mapping but without other modification.
Quoted 2 lines
Upgrading to a 2.6.x kernel may solve the problem, but it needs a lot of effort. Does 2.6.x kernel support 2G physical memory?
It's the same. Some architecture have 36-bit addressing, but I don't know if the latest kernel has the support for this feature for powerpc.
Quoted 48 lines
Quoted 38 lines · Marco Stornelli
Ruksen INANIR ha scritto:
Quoted 2 lines
Is there any side effects of changing the address splitting?
Yes, in this way the application address space is smaller than normal. Some big applications (for example same dbms) might not work. Usually with 2G/2G most of the applications work well.
Quoted 3 lines
What should i change for 2G/2G splitting? should i shift the kernel start? Thanks
Yes in advanced options of the kernel menu, but sometimes it's not easy. Sometimes ago I had to do the same thing but I have to change the kernel code because some operations were hard-coded. Be careful because it's not an easy operation. However I'd suggest you to use the highmem, the memory performance are worse than direct memory mapping, but usually it's not a problem because the overhead is low.
Quoted 25 lines
Quoted 13 lines · Marco Stornelli
Marco Stornelli ha scritto:
Quoted 12 lines
Ruksen INANIR ha scritto:
Quoted 11 lines
Is there a way to increase the lowmem value for ppc. The
MAX_LOW_MEMis defined as max 768 MB. But a value around 1.5 G works with no problem. But when i try to increase this value to 1520 or more, kernel complaints about no space for memory allocation when loading kernel modules. I do not want to use HIGHMEM config. What is the max lowmem value for a ppc system? What other setting are needed to use 1520 MB (or more) as lowmem .
The ppc card has 2G on board memory. 2.4.22 kernel is used.Thanks
_______________________________________________
Linuxppc-embedded mailing list
[email protected]
https://ozlabs.org/mailman/listinfo/linuxppc-embeddedQuoted 4 lines
Quoted 2 lines
With 32-bit arch you may not use more than 1GB to map the memory (minus some space for some kernel operation). The value of 768MB was not there by chance.
Only an additional comment: I meant with the address splitting 3G/1G. To map more than 1GB, you have to change the splitting 2G/2G for example.
_______________________________________________
Linuxppc-embedded mailing list
[email protected]
https://ozlabs.org/mailman/listinfo/linuxppc-embedded_______________________________________________
Linuxppc-embedded mailing list
[email protected]
https://ozlabs.org/mailman/listinfo/linuxppc-embedded
Signature · 7 lines
Marco Stornelli Embedded Software Engineer CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni http://www.coritel.it [email protected] +39 06 72582838