Messages in this thread | | | Date | Wed, 9 Aug 2023 20:11:45 +0800 | From | Liang Li <> | Subject | Re: [PATCH] perf/smmuv3: Add platform id table for module auto loading |
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Hi Yicong,
Thanks for your reply,
On 2023-08-09 14:31, Yicong Yang <yangyicong@huawei.com> wrote: > Hi Barry, Liang, > > On 2023/8/9 13:47, Barry Song wrote: > > On Wed, Aug 9, 2023 at 1:01 PM Liang Li <liliang6@email.cn> wrote: > >> > >> On 2023-08-07 20:22, Yicong Yang <yangyicong@huawei.com> wrote: > >>> From: Yicong Yang <yangyicong@hisilicon.com> > >>> > >>> On ACPI based system the device is probed by the name directly. If the > >>> driver is configured as module it can only be loaded manually. Add the > >>> platform id table as well as the module alias then the driver will be > >>> loaded automatically by the udev or others once the device added. > >>> > >> > >> Please consider revise the long log to clearly express the purpose of the > >> changes in this patch: > >> > >> - What's the exact issue the patch is addressing > >> - Why the changes in this patch can fix the issue or make something working > >> - Consider impact of the changes introduced by this patch > >> > >> These info may help reviewers and maintainers .. and yourself on code merge. > > > > years ago, i found a good doc regarding this, > > https://wiki.archlinux.org/title/Modalias > > > > guess it is because /lib/modules/$(uname -r)/modules.alias fails to contain smmu > > driver without the MODULE_DEVICE_TABLE, isn't it, yicong? > > Yes I think it's the reason. I didn't find summary in kernel docs for the modalias > as well as the uevent mechanism. Arch wiki has a well illustration for the modalias > and suse[1] describes how this is used by the udev for module auto loading. > > For my case I'm using a ACPI based arm64 server and after booting the arm_smmuv3_pmu.ko > is not auto loaded by the udevd since we aren't providing this information. In order > to support this we need to provide this MODULE_DEVICE_TABLE() when the smmu pmu added > as a platform device, then the userspace udev can know which module to load after the > device is added. >
Then what's the purpose of the added '.id_table = ...' line in the previous patch ? <We lost the patch context in this thread.>
Based on above clarification, the updated DEVICE_TABLE would update modalias as expected, right ?
> [1] https://documentation.suse.com/sles/15-SP1/html/SLES-all/cha-udev.html#sec-udev-drivers > > Thanks.
Regards. Liang Li
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