Messages in this thread | | | Subject | Re: [PATCH v2] hpet: Fix missing '=' character in the __setup() code of hpet_mmap_enable | From | Buland Singh <> | Date | Thu, 20 Dec 2018 19:12:55 +0530 |
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On 12/20/18 5:59 PM, Greg KH wrote: > On Thu, Dec 20, 2018 at 05:35:24PM +0530, Buland Singh wrote: >> Commit '3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for >> user processes")' introduced a new kernel command line parameter hpet_mmap, >> that is required to expose the memory map of the HPET registers to >> user-space. Unfortunately the kernel command line parameter 'hpet_mmap' is >> broken and never takes effect due to missing '=' character in the __setup() >> code of hpet_mmap_enable. >> >> Before this patch: >> >> dmesg output with the kernel command line parameter hpet_mmap=1 >> >> [ 0.204152] HPET mmap disabled >> >> dmesg output with the kernel command line parameter hpet_mmap=0 >> >> [ 0.204192] HPET mmap disabled >> >> After this patch: >> >> dmesg output with the kernel command line parameter hpet_mmap=1 >> >> [ 0.203945] HPET mmap enabled >> >> dmesg output with the kernel command line parameter hpet_mmap=0 >> >> [ 0.204652] HPET mmap disabled >> >> Fixes: 3d035f580699 ("drivers/char/hpet.c: allow user controlled mmap for user processes") >> Signed-off-by: Buland Singh <bsingh@redhat.com> >> --- >> drivers/char/hpet.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c >> index 4a22b4b41aef..9bffcd37cc7b 100644 >> --- a/drivers/char/hpet.c >> +++ b/drivers/char/hpet.c >> @@ -377,7 +377,7 @@ static __init int hpet_mmap_enable(char *str) >> pr_info("HPET mmap %s\n", hpet_mmap_enabled ? "enabled" : "disabled"); >> return 1; >> } >> -__setup("hpet_mmap", hpet_mmap_enable); >> +__setup("hpet_mmap=", hpet_mmap_enable);
Hello Greag,
> This has _never_ worked? Since 3.13?
Yes, that's true :)
> Why not just remove the thing as it is obvious no one actually has ever used it. > That would make the code even simpler :)
Data Plane Development Kit (DPDK)[1] provides API that requires the CONFIG_HPET_MMAP kernel configuration option to be enabled[2]. Some end users might want to use the HPET MMAP functionality within the application.
Regards, Buland Singh
[1] https://www.dpdk.org [2] https://doc.dpdk.org/guides-18.08/linux_gsg/enable_func.html
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