Hirokazu Takahashi <[EMAIL PROTECTED]> writes: > Hi Vivek, > > > > Hi Vivek and Eric, > > > > > > IMHO, why don't we swap not only the contents of the top 640K > > > but also kernel working memory for kdump kernel? > > > > > > Initial patches of kdump had adopted the same approach but given the > > fact devices are not stopped during transition to new kernel after a > > panic, it carried inherent risk of some DMA going on and corrupting the > > new kernel/data structures. Hence the idea of running the kernel from a > > reserved location came up. This should be DMA safe as long as DMA is not > > misdirected. > > I see, that makes sense. > But I'm not sure yet that it's safe to access the top of 640MB. 640K?
> I wonder how kmalloc(GFP_DMA) works in a kdump kernel. All that happens there is a one line change to vmlinux.lds.S that causes the kernel to live at a different physical and virtual address. So everything works as normal. I do agree that it is risky to use the first 640K for normal work. But on the list of things to fix it is a minor war, and even if we back up that region of memory we don't need to use it. There are still remain a lot of code reviews to ensure the code is generally safe. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
