On Thu, Feb 14, 2019 at 7:06 PM liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx> wrote: > > 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. You haven't given any reason why we need to support this. > >>>> +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. Actually, looking at do_mounts.c, it is the partition UUID and label. See PARTUUID and PARTLABEL. > 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. Yes, userspace has more capabilities for mounting. > MTD device may has label, but it is not suitable for all block device. MTD is special... > 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" . There is simply no way we are putting Linux device names into DT. Besides just being Linux specific, the device names are not guaranteed to be stable. Rob
