On Mon, Nov 16, 2015 at 1:10 PM, Jerry Hoemann <jerry.hoemann@xxxxxxx> wrote: > On Mon, Nov 16, 2015 at 11:00:20AM -0800, Dan Williams wrote: >> On Mon, Nov 16, 2015 at 10:38 AM, Jerry Hoemann <jerry.hoemann@xxxxxxx> wrote: >> > >> > The NVDIMM code in the kernel supports an IOCTL interface to user >> > space based upon the Intel Example DSM: >> > >> > http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf >> > >> > This interface cannot be used by other NVDIMM DSMs that support >> > incompatible functions. >> > >> > This patch set adds a generic "passthru" IOCTL interface which >> > is not tied to a particular DSM. >> > >> > A new _IOC_NR ND_CMD_PASSTHRU == "100" is added for the pass thru call. >> > >> > The new data structure nd_passthru_pkg serves as a wrapper for the passthru >> > calls. This wrapper supplies the data that the kernel needs to >> > make the _DSM call. >> > >> > Unlike the definitions of the _DSM functions themselves, the nd_passthru_pkg >> > provides the calling information (input/output sizes) in an uniform >> > manner making the kernel marshaling of the arguments straight >> > forward. >> > >> > This shifts the marshaling burden from the kernel to the user >> > space application while still permitting the kernel to internally >> > call _DSM functions. >> > >> > To make the resultant kernel code easier to understand the existing >> > functions acpi_nfit_ctl and __nd_ioctl were renamed to .*_intel to >> > denote calling mechanism as in 4.3 tailored to the Intel Example DSM. >> > New functions acpi_nfit_ctl_passthru and __nd_ioctl_passthru were >> > created to supply the pass thru interface. >> >> Let's not do the _intel vs _passthru split. I want to convert the >> existing commands over to this new interface and deprecate the old >> ioctl-command formats. I.e. it isn't the case that this will be a >> always be a blind "passthru" mechanism, the kernel will need to crack >> open this payload in some circumstances. > > > I'm confused. > > In this version there is only 1 ioctl 'N'. The pass thru is using > number 100. This is what I thought you wanted from prior comments. It is indeed, I like that change. > The split are for internal functions that deal specifically w/ > the argument marshaling code and copy-in/copy-out. These mechanisms > are different. > > I understand that you want to switch over, but don't you (at least for > the time being) need to keep the old marshaling code for the current > use case? I was assuming a sequence like: > 1. The pass thru code gets submitted. > 2. The current tools are converted over to using the pass thru, > 3. The marshaling code using nd_cmd_in_size etc., would then > be removed. > > Are you wanting to make one big change and not in separate steps? I want to do it in separate steps, I'd just like to see cmd number 100 added to the existing __nd_ioctl and acpi_nfit_ctl routines. That plus quibbling about the name "ND_CMD_PASSTHRU". Given the plans to eventually replace the existing commands we can call it something like 'ND_DSM_GENERIC'. > Now I don't currently have provision for "snooping" out specific functions > in the pass thru flow. The 4.3 code doesn't do that either per se. It > will do the calls asked of it from the user. > > Snooping is a feature that could be added, but since I'm not sure your > plans here, the best I can do at the moment is to put in a hook to > a function that is a no-op. The meat of this function to be added > when plans become more firm. Do you have more specific info here? No need to add the snooping support now, I only made the comment in reference to the "passthru" name. We can add snooping support later after we finalize this initial marshaling code. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
