Messages in this thread Patch in this message | | | Date | Sun, 12 Jan 2003 02:13:01 -0500 | From | Brian Gerst <> | Subject | Re: 2.5.55/.56 instant reboot problem on 486 |
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Mikael Pettersson wrote: > My '94 vintage 486 has problems booting 2.5.55 and 2.5.56. > When it fails, the boot gets to loading the kernel and > printing "Ok, booting the kernel.". Then there is a short > pause (line a tenth of a second) and the machine reboots. > > After doing a binary search with "for(;;);" statements > (printk doesn't work this early) I found that the reboot > occurs in arch/i386/mm/init.c:kernel_physical_mapping_init(): > (start_kernel() -> setup_arch() -> paging_init() -> > pagetable_init() -> kernel_physical_mapping_init()) >
The problem is that one_page_table_init() pulls the rug out from under the kernel by installing a new page table before setting it up. A 486 has a small TLB so any miss will cause a triple fault and reset. Try this patch and see if it fixes it.
-- Brian Gerst diff -urN linux-2.5.56/arch/i386/mm/init.c linux/arch/i386/mm/init.c --- linux-2.5.56/arch/i386/mm/init.c Sun Jan 12 00:16:22 2003 +++ linux/arch/i386/mm/init.c Sun Jan 12 01:48:28 2003 @@ -71,12 +71,16 @@ */ static pte_t * __init one_page_table_init(pmd_t *pmd) { - pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE); - set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE)); - if (page_table != pte_offset_kernel(pmd, 0)) - BUG(); + if (pmd_none(*pmd)) { + pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE); + set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE)); + if (page_table != pte_offset_kernel(pmd, 0)) + BUG(); - return page_table; + return page_table; + } + + return pte_offset_kernel(pmd, 0); } /* | |