usermode linux without MMU - fosdem2026 kernel devroom

Transcript

1. usermode linux without MMU  1 
2. Overview CONFIG_MMU=n 2 
3. nommu port of UML !MMU 3 
4. User Mode Linux (UML) 4 
5. UML (cont'd) mm/nommu.c 5 
6. hard to find bugs of nommu diff --git a/mm/nommu.c b/mm/nommu.c index 385b0c15add8..0c708f85408d 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -573,7 +573,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma) VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start); vma_iter_config(&vmi, vma->vm_start, vma->vm_end); - if (vma_iter_prealloc(&vmi, vma)) { + if (vma_iter_prealloc(&vmi, NULL)) { pr_warn("Allocation of vma tree for process %d failed\n", current->pid); return -ENOMEM; 6 
7. alternatives 7 
8. implementation (nommu UML) 8 
9. implementation CONFIG_MMU=n 9 
10. nommu architecture 10 
11. nommu UML binfmt_elf_fdpic 11 
12. how syscall works syscall SIGSYS rip fs fp current sys_call_table 12 
13. limitations exit(2) 13 
14. integration busybox-nommu musl-nommu 00:02 14 
15. showcases 15 
16. testing usecase 16 
17. Identity added: /home/tazaki/.ssh/id_rsa (tazaki@ikb-07-27) ikb-h07-29-noble:~/work/nabla-linux/linux-um-nommu% 00:01 (none):/# /r 00:05 17 
18. KUnit test Identity added: /home/tazaki/.ssh/id_rsa (tazaki@ikb-07-27) ikb-h07-29-noble:~/work/nabla-linux/linux-um-nommu% 00:03 18 
19. performance 19 
20. discussion: what was this ? 20 
21. summary 21 