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Date: Thu, 13 May 2004 14:52:53 +0800
From: wuming <wuming@ict.ac.cn>
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Subject: problems on D-cache alias in 2.4.22
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 I am developing in linux-2.4.22 on the machine with virtual address
indexed and physical
address tagged. But when I compile some application programs, I met the
following error:

cc1: internal compiler error: Segmentation fault

I have searched about this error from internet, it's due to some
hardware fault or
a wrong pte fault handler. Because my machine have D-cache aliasing, so
I think
this error should be due to a wrong pte fault handler. After my painful
kernel hacking,
I found some strange problems and it's in function __update_cache( ):

void __update_cache(struct vm_area_struct *vma, unsigned long address,
pte_t pte)
{
unsigned long addr;
struct page *page;

if (!cpu_has_dc_aliases)
return;

page = pte_page(pte);

/*This printk is added by myself*/
printk("<1>valid page:%d\tpage mapping:0x%p\tpage flags:%d\n",\
VALID_PAGE(page), page->mapping, (page->flags & (1UL << PG_dcache_dirty)));

if (VALID_PAGE(page) && page->mapping &&
(page->flags & (1UL << PG_dcache_dirty))) {
if (pages_do_alias((unsigned long) page_address(page), address &
PAGE_MASK)) {
addr = (unsigned long) page_address(page);
flush_data_cache_page(addr);
}
ClearPageDcacheDirty(page);
}
}

When my kernel is running, I found the condition "page->mapping" and
"(page->flags & (1UL << PG_dcache_dirty))"
will never be true at the same time. so the function
flush_data_cache_page( ) will never be called.
Then I commented the two condition, the compiler error disappeared.
I do not understand the phenomenon very clearly, so I need some help.