2009/6/24 Jamie Lokier <jamie@xxxxxxxxxxxxx>: > Pavel Machek wrote: >> On Tue 2009-06-23 20:07:23, Marco wrote: >> > You are talked about journaling. This schema works well for a disk, but >> > what about a piece of ram? What about a crazy kernel that write in that >> > area for a bug? Do you remember for example the e1000e bug? It's not >> >> I believe you need both journaling *and* write protection. How do you >> handle power fault while writing data? > > I think this is basically right. > > write protection for the crazy kernels, and journalling for > powerfail/crash during updates. > > Journalling can be extremely simple. It can be just one memory block > at a fixed location, double-buffering all writes. > > Pramfs already has checksums, which makes that easier. You just write > to the buffer area first, with checksum, then write to the final area. > Mount looks at the buffer area, and if the checksum is fine, copies > the contents to the destination block. > > That's all it takes to be resistant against power failures and crashes > during writes. Probably <100 lines of code. > > -- Jamie > It seems a reasonable request. Marco -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
