Date: Tue, 8 Mar 2005 13:49:24 -0800 From: <Vijay.Singh@nokia.com> To: <dnelson@allantgroup.com> Cc: freebsd-hackers@freebsd.org Subject: RE: partial memory dump Message-ID: <E40595640FD457418D8F9005C2BEC84901BE6F3C@mvebe001.americas.nokia.com>
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Hi, thanks for the quick reply. I do indeed write the bitmap, which is a = part of the sysdump_hdr structure to the disk. The disk routine does not = currently report that it had to miss any block. Here is what I get from = dadump(). dumpsys() in machdep.c dumping to dev 20401, offset 0 dadump() dodump: 1 USRSTACK: 0xbfbfc000 to 0xe6fa5000 Maxmem: 524288, secsize: 512 dumplo: 0, num: 84872, size: 2097152 next block to write: 90640 @ 8 blocks/req Dumping bitmap at addr e6fa5000 to sec 16210, 88 sectors next block to write: 90776 @ 8 blocks/req Dumping 0x2960 pages of memory to sec 0x16298, 0x14b00 sectors This version of dadump() does not implement write combining yet. Do you = think savecore is not able to find the data blocks correctly in the = swap? br vijay -----Original Message----- From: ext Dan Nelson [mailto:dnelson@allantgroup.com] Sent: Tuesday, March 08, 2005 1:40 PM To: Singh Vijay (Nokia-NET/MtView) Cc: freebsd-hackers@freebsd.org Subject: Re: partial memory dump In the last episode (Mar 08), Vijay.Singh@nokia.com said: > Hello all. I am trying to allow a FreeBSD based kernel to crash dump > even if configured swap is not enough to fill entire physical memory. > This is because there could be 2G RAM on the system. I assume that > most pages would not be mapped. >=20 > The algorithm to do this is to have a bitmask, with bits set for > pages: from 0 to Maxmem, and then adding pages from USRSTACK to > vm_map_max(kmem_map). This is done in scsi_da.c, dadump() routine. I > am able to get the dump, and after savecore collects it from swap I > get the kernel and core files. However I am not able to get the stack > trace. I think you also need to write that bitmap to disk so that savecore can read it and put the data blocks in the right place in the vmcore file.=20 You want to end up a with a sparse file, with blank spots every place dadump skipped a block. --=20 Dan Nelson dnelson@allantgroup.com
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