Hi,
In article <[email protected]>,
Quoted 11 lines · [email protected] (Timur Tabi) writes:
** Reply to message from Robert Kaiser <[email protected]> on Tue, 9 Jan 2001 23:17:11 +0100
Quoted 6 lines
temp = mk_pte_phys(__pa(vaddr), PAGE_KERNEL); *pte = temp;where temp is declared "volatile
pte_t". I inserted test-prints between the above two lines. Accoding to that, the _first_ line , i.e. the evaluation of themk_pte_phys()macro is causing the crash!
Quoted 8 lines
In that case, it's either a compiler bug or a race condition.
Compiling this source file with the -S option will generate an assembly output. The output should be the same regardless of whether you use the temp variable or not. That will answer the question as to what the cause is. If you're lucky, it's a compiler bug, because they're easier to fix.
I thought that by declaring temp "volatile" I could force the compiler to not optimize it away, i.e. make sure that the evaluation of the mk_pte_phys() macro and the assignment to *pte indeed get seperated. Is this not the case ?
Anyway, the actual code I'm using has debug output in between the lines, so it looks more like this:
*((volatile unsigned char*)0xb8000) = '1'; temp = mk_pte_phys(__pa(vaddr), PAGE_KERNEL); *((volatile unsigned char*)0xb8000) = '2'; *pte = temp; *((volatile unsigned char*)0xb8000) = '3';
When the system crashes, just before the BIOS clears the screen, I can clearly see a '2' in the upper left corner of the screen.
----------------------------------------------------------------
Robert Kaiser email: [email protected]
SYSGO RTS GmbH
Am Pfaffenstein 14 phone: (49) 6136 9948-762
D-55270 Klein-Winternheim / Germany fax: (49) 6136 9948-10
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