On 2019-02-14 04:30, Rob Herring wrote: > On Wed, Feb 13, 2019 at 7:51 AM liaoweixiong > <liaoweixiong@xxxxxxxxxxxxxxxxx> wrote: >> >> >> On 2019-01-31 00:07, Rob Herring wrote:> On Wed, Jan 23, 2019 at >> 08:05:13PM +0800, liaoweixiong wrote: >>>> Create DT binding document for blkoops. >>>> >>>> Signed-off-by: liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx> >>>> --- >>>> .../devicetree/bindings/pstore-block/blkoops.txt | 32 ++++++++++++++++++++++ >>> >>> /bindings/pstore/... >>> >>> I wouldn't call it blkoops either. I believe ramoops is called that to >>> maintain compatibility keeping the same kernel module name that >>> preceeded pstore. >>> >> >> Fixed. >> >> In addition, I don't known whether should we move >> ramreserved-memory/ooos.txt to /bindings/pstore. This is for maintainer >> to decide, and do it on other patch. >> >>>> MAINTAINERS | 1 + >>>> 2 files changed, 33 insertions(+) >>>> create mode 100644 Documentation/devicetree/bindings/pstore-block/blkoops.txt >>>> >>>> diff --git a/Documentation/devicetree/bindings/pstore-block/blkoops.txt b/Documentation/devicetree/bindings/pstore-block/blkoops.txt >>>> new file mode 100644 >>>> index 0000000..a25835b >>>> --- /dev/null >>>> +++ b/Documentation/devicetree/bindings/pstore-block/blkoops.txt >>>> @@ -0,0 +1,32 @@ >>>> +Blkoops oops logger >>>> +=================== >>>> + >>>> +Blkoops provides a block partition for oops, excluding panics now, so they can >>>> +be recovered after a reboot. >>>> + >>>> +Any space of block partition will be used for a circular buffer of oops records. >>>> +These records have a configurable size, with a size of 0 indicating that they >>>> +should be disabled. >>>> + >>>> +"partition-size" and at least one of "dmesg-size" or "pmsg-size" must be set >>>> +non-zero, but are otherwise optional as listed below. >>>> + >>>> +Blkoops will take value from Kconfig if device tree do not set, but settings >>>> +from module parameters can also overwrite them. >>> >>> That's all kernel details not relevant to the binidng. >>> >> >> Deleted. >> >>>> + >>>> +Required properties: >>>> + >>>> +- compatible: must be "blkoops". >>>> + >>>> +- partition-size: size in kbytes, must be a multiple of 4. >>> >>> This seems unnecessary given a partition has a known size. >>> >> >> partition-size is necessary for psotre/blk. User should tell pstore/blk >> how large space can it use. > > The partition table says how big a partition is. If you only want to > use part of it, then make the partition smaller or use a file system. > This is a solved problem, so we don't need a new way in DT to handle > this. > You are right, partition size is known and pstore/blk can get it automatically from specified block device. I will try to do it on next version patch. But i prefer to rename partition-size to total-size and move it to optional properties. Total-size means how big space pstore/blk can use. It is not only about partition size as pstore/blk can use ram if no partition specified. So, I will process as follow logic: 1. If specify total size, use total size. 2. If no total size but specify partition, get size from partition. >>>> +Optional properties: >>>> + >>>> +- partition-path: strings must begin with "/dev", tell blkoops which partition >>>> + it can used. If it is not set, blkoops will drop all data when reboot. >>> >>> No. '/dev/...' is a Linux thing and doesn't belong in DT. >>> >>> You should define a partition UUID and/or label and the kernel can find >>> the right partition to use. >>> >> >> pstore/blk do general read/write by filp_open/kernel_read/kernel_write, >> which need device path. >> In addition, i have no idea how to use UUID and/or label to do general >> read/write on kernel layer, can you give me a tip? > > The kernel can mount a filesystem by label or UUID though I think > those are filesystem UUID and label, not partition UUID and label. But > certainly bootloaders find the EFI system partition by UUID. > As your words, those are file system UUID and label, not partition UUID/label. Pstore is a file system, there is no other file system any more for specified partition. Pstore/blk can't get specified partition by UUID or label. As far as i know, block device manager on user space scans each block device and matches file system table to get UUID and label. Not even all file systems have UUID/label. MTD device may has label, but it is not suitable for all block device. How if i cancel the prefix requirement for /dev and add it to the codes? Then rename partition-path to block-device, by this, DT property may be "mmcblk0p10" or "sda6" . > Rob > -- liaoweixiong
