On Wed, Jun 28, 2023 at 09:50:00PM +0530, Mukesh Ojha wrote: > > > On 6/28/2023 9:15 PM, Greg KH wrote: > > On Wed, Jun 28, 2023 at 06:04:27PM +0530, Mukesh Ojha wrote: > > > Minidump is a best effort mechanism to collect useful and predefined data > > > for first level of debugging on end user devices running on Qualcomm SoCs. > > > It is built on the premise that System on Chip (SoC) or subsystem part of > > > SoC crashes, due to a range of hardware and software bugs. Hence, the > > > ability to collect accurate data is only a best-effort. The data collected > > > could be invalid or corrupted, data collection itself could fail, and so on. > > > > > > Qualcomm devices in engineering mode provides a mechanism for generating > > > full system ramdumps for post mortem debugging. But in some cases it's > > > however not feasible to capture the entire content of RAM. The minidump > > > mechanism provides the means for selecting which snippets should be > > > included in the ramdump. > > > > > > Minidump kernel driver implementation is divided into two parts for > > > simplicity, one is minidump core which can also be called minidump > > > frontend(As API gets exported from this driver for registration with > > > backend) and the other part is minidump backend i.e, where the underlying > > > implementation of minidump will be there. There could be different way > > > how the backend is implemented like Shared memory, Memory mapped IO > > > or Resource manager(gunyah) based where the guest region information is > > > passed to hypervisor via hypercalls. > > > > > > Minidump Client-1 Client-2 Client-5 Client-n > > > | | | | > > > | | ... | ... | > > > | | | | > > > | | | | > > > | | | | > > > | | | | > > > | | | | > > > | | | | > > > | +---+--------------+----+ | > > > +-----------+ qcom_minidump(core) +--------+ > > > | | > > > +------+-----+------+---+ > > > | | | > > > | | | > > > +---------------+ | +--------------------+ > > > | | | > > > | | | > > > | | | > > > v v v > > > +-------------------+ +-------------------+ +------------------+ > > > |qcom_minidump_smem | |qcom_minidump_mmio | | qcom_minidump_rm | > > > | | | | | | > > > +-------------------+ +-------------------+ +------------------+ > > > Shared memory Memory mapped IO Resource manager > > > (backend) (backend) (backend) > > > > > > > > > Here, we will be giving all analogy of backend with SMEM as it is the > > > only implemented backend at present but general idea remains the same. > > > > If you only have one "backend" then you don't need the extra compexity > > here at all, just remove that whole middle layer please and make this > > much simpler and smaller and easier to review and possibly accept. > > > > We don't add layers when they are not needed, and never when there is no > > actual user. If you need the extra "complexity" later, then add it > > later when it is needed as who knows when that will ever be. > > > > Please redo this series based on that, thanks. > > I already followed without this middle layer till v3 since without > the middle layer it will be end up with lot of code duplication if there > is another backend. But as this series does not have such a thing, only add it when needed please. Don't make us review a whole bunch of stuff that is not actually used here. Would you want to review such a thing? > We already have other backend implementation in the downstream, if you > want to see them, i will try to post them in upcoming series.. Ok, so if you already have it, yes, post it as part of the series, otherwise such a layer makes no sense. thanks, greg k-h
