Untranslated page fault with pgprot_noncached()





.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ height:90px;width:728px;box-sizing:border-box;
}







0















I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.



Currently, I am experimenting with SMMU disabled.
Here is the flow:



ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?



phys_addr = bus_addr;



mmap (...phys_addr);



vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);



remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));



But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.



Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.



Thanks in advance !!










share|improve this question























  • Can somebody please comment on this?

    – PBang
    Nov 26 '18 at 10:04


















0















I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.



Currently, I am experimenting with SMMU disabled.
Here is the flow:



ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?



phys_addr = bus_addr;



mmap (...phys_addr);



vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);



remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));



But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.



Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.



Thanks in advance !!










share|improve this question























  • Can somebody please comment on this?

    – PBang
    Nov 26 '18 at 10:04














0












0








0








I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.



Currently, I am experimenting with SMMU disabled.
Here is the flow:



ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?



phys_addr = bus_addr;



mmap (...phys_addr);



vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);



remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));



But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.



Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.



Thanks in advance !!










share|improve this question














I use 2 ARM boards for DMA remote write and read.
With SMMU enabled, I faced an issue while fetching the physical address which is required for mapping the physical address to the kernel address in the user space.



Currently, I am experimenting with SMMU disabled.
Here is the flow:



ker_addr = (u64) dma_alloc_coherent (... dma_addr_t bus_addr); // does casting cause any issue?



phys_addr = bus_addr;



mmap (...phys_addr);



vma->vm_page_prot = pgprot_noncached(vma>vm_page_prot);



remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
vma->vm_end - vma->vm_start, vma->vm_page_prot));



But, resulted in untraslated page fault.
When commented pgprot_noncached in the custom driver, I found no error.
Please help me know the cause.



Also, is it recommended to replace remap_pfn_range() with dma_mmap_coherent()?
As far as I know, remap_pfn_range() deals with the physical address where as dma_mmap_coherent() deals with the bus address given by dma_alloc_coherent().
Please let me know if it is different.



Thanks in advance !!







arm dma pci-e






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 22 '18 at 11:54









PBangPBang

11




11













  • Can somebody please comment on this?

    – PBang
    Nov 26 '18 at 10:04



















  • Can somebody please comment on this?

    – PBang
    Nov 26 '18 at 10:04

















Can somebody please comment on this?

– PBang
Nov 26 '18 at 10:04





Can somebody please comment on this?

– PBang
Nov 26 '18 at 10:04












0






active

oldest

votes












Your Answer






StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});














draft saved

draft discarded


















StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53430470%2funtranslated-page-fault-with-pgprot-noncached%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown

























0






active

oldest

votes








0






active

oldest

votes









active

oldest

votes






active

oldest

votes
















draft saved

draft discarded




















































Thanks for contributing an answer to Stack Overflow!


  • Please be sure to answer the question. Provide details and share your research!

But avoid



  • Asking for help, clarification, or responding to other answers.

  • Making statements based on opinion; back them up with references or personal experience.


To learn more, see our tips on writing great answers.




draft saved


draft discarded














StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53430470%2funtranslated-page-fault-with-pgprot-noncached%23new-answer', 'question_page');
}
);

Post as a guest















Required, but never shown





















































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown

































Required, but never shown














Required, but never shown












Required, but never shown







Required, but never shown







Popular posts from this blog

Guess what letter conforming each word

Port of Spain

Run scheduled task as local user group (not BUILTIN)