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| Would it be smart to map all physical addresses to virtua... https://forum.osdev.org/viewtopic.php?f=15&t=31115 |
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| Author: | Ycep [ Sat Dec 24, 2016 8:16 am ] |
| Post subject: | Would it be smart to map all physical addresses to virtua... |
...l while boot? If not, why? What would be pros and cons of it? |
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| Author: | BrightLight [ Sat Dec 24, 2016 9:23 am ] |
| Post subject: | Re: Would it be smart to map all physical addresses to virtu |
It makes perfect sense to map all physical addresses to virtual address during booting. It makes some things (e.g. ACPI table access, PCIe configuration, ...) easier to do. For 64-bit systems, it makes sense to leave the lower half of the 48-bit address space for general purpose use, and the upper half to map all physical addresses. |
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| Author: | Ycep [ Sat Dec 24, 2016 10:53 am ] |
| Post subject: | Re: Would it be smart to map all physical addresses to virtu |
What is wrong with this then... Code: PageDir* d=(PageDir*)AllocBlock(12288); memclr(d,sizeof(PageDir)); uint page=0, frame=0; for(uint j=0;j<SystemBootInfo->memoryLo/4096;j++) { PageTable* t=new PageTable; for(uint i=0;i<1024;i++,frame+=4096) { AddAtrib(&page,pteUser); SetFrame(&page,(uint)frame); AddAtrib(&page,ptePresent); t->entries[pteIndex(frame)]=frame; } AddAtrib(&d->entries[j], pdeWritable); AddAtrib(&d->entries[j], pdePresent); SetFrame(&d->entries[j], (uint)t); } AddAtrib(), SetFrame() and pteIndex() are checked to be working. |
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| Author: | iansjack [ Sat Dec 24, 2016 12:13 pm ] |
| Post subject: | Re: Would it be smart to map all physical addresses to virtu |
What makes you think anything is wrong with it? Have you checked the generated page table to make sure it is correct? |
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| Author: | Ycep [ Sun Dec 25, 2016 10:12 am ] |
| Post subject: | Re: Would it be smart to map all physical addresses to virtu |
Finally I finished the skeleton of my memory managament. ( I sound nerdy) |
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