On 30 December 2014 at 09:25, Dave Young <dyoung@xxxxxxxxxx> wrote: > On 12/29/14 at 09:22am, Ard Biesheuvel wrote: >> On 26 December 2014 at 09:35, Dave Young <dyoung@xxxxxxxxxx> wrote: >> > On 12/22/14 at 07:08pm, Ard Biesheuvel wrote: >> >> This series was split off from the UEFI virtmap for kexec series that I posted >> >> earlier today. The main purpose is to deal with the need to classify memory >> >> ranges as RAM or non-RAM in a consistent and comprehensive manner. This series >> >> applies on top of the other series. >> >> >> >> Patch #1 avoids an early panic if the UEFI memory map is available but UEFI >> >> support itself fails to initialize. In this case, there is no need to panic >> >> early, and we have a better chance of being able to inform the user if we deal >> >> with this error condition at a later time. >> >> >> >> Patch #2 adds iomem resource registration of UEFI memory regions. This is >> >> necessary because otherwise, drivers could potentially claim regions that >> >> are in active use by the firmware. This applies to both MMIO (NOR flash, RTC) >> >> and RAM ranges (runtime services code and data). >> >> >> >> Patch #3-6 adds support to UEFI and non-UEFI code paths to record all memory >> >> known to the system in the 'physmem' memblock table (if enabled). This fulfils >> >> a need in the /dev/mem and (upcoming) ACPI layers to be able to classify ranges >> >> as being backed by normal RAM even if they are not covered by the 'memory' >> >> memblock table, and are hence not covered by the linear direct mapping. >> >> The physmem code is pre-existing code that only needs minor tweaking to be made >> >> suitable for this purpose. >> >> >> >> Patch #7 enables the 'physmem' memblock table for arm64, and wires it into the >> >> handling of /dev/mem mappings, both to decide whether it should be mapped as >> >> MT_NORMAL, and whether read-write access can be allowed. (Non-RAM regions can >> >> be mapped read-write as long as they are not claimed by a driver in the iomem >> >> resource table. RAM regions can only be mapped read-only, and only if they are >> >> not covered by the 'memory' memblock table, and hence not covered by the linear >> >> mapping) >> >> >> >> Finally, patch #8 changes the way the virtual memory map is handled by the >> >> early UEFI code. Specifically, it memblock_remove()s rather than _reserves() >> >> UEFI reserved RAM regions, so that they are removed entirely from the linear >> >> mapping. >> >> >> >> Ard Biesheuvel (8): >> >> arm64/efi: use UEFI memory map unconditionally if available >> >> arm64/efi: register UEFI reserved regions as iomem resources >> >> memblock: add physmem to memblock_dump_all() output >> >> memblock: introduce memblock_add_phys() and memblock_is_physmem() >> >> of: fdt: register physmem in early_init_dt_scan_memory() >> >> arm64/efi: register physmem in reserve_regions() >> >> arm64: use 'physmem' memblock to improve CONFIG_STRICT_DEVMEM handling >> >> arm64/efi: memblock_remove rather than _reserve UEFI reserved RAM >> > >> > Ard, It is much cleaner for this splitting. >> > >> >> Thanks for having a look. >> >> > I wonder if some of them can become general code such as register reserved >> > regions as iomem resources? >> > >> >> AFAICT, the x86 code adds reservations for such regions to the E820 >> memory map, which in turn is used to memblock_reserve() the actual >> memory. Also, sharing of the RTC is handled with a dedicated mutex in >> the runtime services wrapper code (and x86 does not even use the time >> related runtime services as they are broken on many firmware >> implementations) so blindly applying the same logic to x86 or ia64 >> would likely break stuff. > > Ok, I think bootloader will pass the E820 ranges though it can not tell > which region is for what. > >> >> Do you (or Mark) have any feedback on the utility of this series in >> the ACPI context? I failed to mention in the cover letter that >> memblock_is_physmem() now serves the purpose of page_is_ram(), i.e., >> whether a physical region is backed by a slice of RAM that was left >> out of the kernel's linear mapping. > > I will do some test later along with the stable mapping stuff. > Cheers. > BTW, with previous stable mapping patches on modified 3.18 tree kexec kernel > panics because of damaged efi mempry map arrays. It contains some > random value instead of right addresses so that virt_to_phys return > same value for vendor field. Will do more debugging maybe I missed something. > Any clue for debugging above issue will be appreciated. > No clues, unfortunately. The memory map is not used after early boot, so it may be getting clobbered at any point between the first boot and the second boot. -- Ard. -- 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
