On Mon, 2014-09-08 at 15:06 +0100, Mark Rutland wrote: > Hi Mark, > > On Mon, Sep 08, 2014 at 02:31:42PM +0100, Mark Salter wrote: > > Commit 86c8b27a01cf: > > "arm64: ignore DT memreserve entries when booting in UEFI mode > > > > prevents early_init_fdt_scan_reserved_mem() from being called for > > arm64 kernels booting via UEFI. This was done because the kernel > > will use the UEFI memory map to determine reserved memory regions. > > That approach has problems in that early_init_fdt_scan_reserved_mem() > > also reserves the FDT itself and any node-specific reserved memory. > > By chance of some kernel configs, the FDT may be overwritten before > > it can be unflattened and the kernel will fail to boot. More subtle > > problems will result if the FDT has node specific reserved memory > > which is not really reserved. > > That doesn't sound like fun; apologies for allowing such brokenness > through in the first place. Heh. It was obvious that DT unflattening was broken, but bisecting didn't help much because I kept finding patches which when reverted made the problem go away even though they obviously weren't the cause. > > [...] > > > + /* > > + * Delete all memory reserve map entries. When booting via UEFI, > > + * kernel will use the UEFI memory map to find reserved regions. > > + */ > > + num_rsv = fdt_num_mem_rsv(fdt); > > + for (i = 0; i < num_rsv; i++) > > + fdt_del_mem_rsv(fdt, i); > > I don't think that's right. Won't the memreserve entries shift down by > one each time we call fdt_del_mem_rsv? > > Shouldn't this be something like: > > while (fdt_num_mem_rsv(fdt)) > fdt_del_mem_rsv(fdt, 0); > > Or we could count downwards. > Sigh. Yes, you are right. I only tested with one reserved region. I think counting down would be the way to go. I'll send a fixed patch shortly. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
