From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hanjun Guo Subject: Re: [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI Date: Tue, 20 Jan 2015 20:17:52 +0800 Message-ID: <54BE4770.6000100@linaro.org> References: <1421247905-3749-1-git-send-email-hanjun.guo@linaro.org> <1421247905-3749-5-git-send-email-hanjun.guo@linaro.org> <20150119114255.GF11835@e104818-lin.cambridge.arm.com> <20150119135144.GI11835@e104818-lin.cambridge.arm.com> <20150119151350.21B65C40948@trevor.secretlab.ca> <54BD3803.6020307@redhat.com> <20150119175233.GK11835@e104818-lin.cambridge.arm.com> <20150119180122.GJ21553@leverpostej> <54BE1FEA.5040109@linaro.org> <20150120111032.GB15924@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-pd0-f175.google.com ([209.85.192.175]:39968 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752687AbbATMS3 (ORCPT ); Tue, 20 Jan 2015 07:18:29 -0500 Received: by mail-pd0-f175.google.com with SMTP id fl12so9746603pdb.6 for ; Tue, 20 Jan 2015 04:18:29 -0800 (PST) In-Reply-To: <20150120111032.GB15924@leverpostej> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Mark Rutland Cc: Catalin Marinas , "jcm@redhat.com" , "grant.likely@linaro.org" , Ard Biesheuvel , "linaro-acpi@lists.linaro.org" , Will Deacon , "wangyijing@huawei.com" , Rob Herring , Lorenzo Pieralisi , Al Stone , Timur Tabi , "linux-acpi@vger.kernel.org" , Charles Garcia-Tobin , "phoenix.liyi@huawei.com" , Robert Richter , Jason Cooper , Arnd Bergmann , Marc Zyngier , Mark Brown , Bjorn Helgaas , linux-arm-kernel@lists.infradead.o On 2015=E5=B9=B401=E6=9C=8820=E6=97=A5 19:10, Mark Rutland wrote: > On Tue, Jan 20, 2015 at 09:29:14AM +0000, Hanjun Guo wrote: >> On 2015=E5=B9=B401=E6=9C=8820=E6=97=A5 02:01, Mark Rutland wrote: >>> On Mon, Jan 19, 2015 at 05:52:33PM +0000, Catalin Marinas wrote: >>>> On Mon, Jan 19, 2015 at 04:59:47PM +0000, Jon Masters wrote: >>>>> On 01/19/2015 10:13 AM, Grant Likely wrote: >>>>>> On Mon, 19 Jan 2015 13:51:45 +0000 >>>>>> , Catalin Marinas >>>>>> wrote: >>>>>>> On Mon, Jan 19, 2015 at 11:55:32AM +0000, Ard Biesheuvel wrote: >>>>>>>> On 19 January 2015 at 11:42, Catalin Marinas wrote: >>>>>>>>> On Wed, Jan 14, 2015 at 03:04:52PM +0000, Hanjun Guo wrote: >>>>>>>>>> From: Al Stone >>>>>>>>>> >>>>>>>>>> Introduce one early parameters "off" and "force" for "acpi",= acpi=3Doff >>>>>>>>>> will be the default behavior for ARM64, so introduce acpi=3D= force to >>>>>>>>>> enable ACPI on ARM64. >>>>>>>>>> >>>>>>>>>> Disable ACPI before early parameters parsed, and enable it t= o pass >>>>>>>>>> "acpi=3Dforce" if people want use ACPI on ARM64. This ensure= s DT be >>>>>>>>>> the prefer one if ACPI table and DT both are provided at thi= s moment. >>>>>>>>> [...] >>>>>>>>>> --- a/arch/arm64/kernel/setup.c >>>>>>>>>> +++ b/arch/arm64/kernel/setup.c >>>>>>>>>> @@ -62,6 +62,7 @@ >>>>>>>>>> #include >>>>>>>>>> #include >>>>>>>>>> #include >>>>>>>>>> +#include >>>>>>>>>> >>>>>>>>>> unsigned int processor_id; >>>>>>>>>> EXPORT_SYMBOL(processor_id); >>>>>>>>>> @@ -388,6 +389,8 @@ void __init setup_arch(char **cmdline_p) >>>>>>>>>> early_fixmap_init(); >>>>>>>>>> early_ioremap_init(); >>>>>>>>>> >>>>>>>>>> + disable_acpi(); >>>>>>>>>> + >>>>>>>>>> parse_early_param(); >>>>>>>>>> >>>>>>>>>> /* >>>>>>>>> >>>>>>>>> Did we get to any conclusion here? DT being the preferred one= is fine >>>>>>>>> when both DT and ACPI are present but do we still want the ke= rnel to >>>>>>>>> ignore ACPI altogether if DT is not present? It's a bit harde= r to detect >>>>>>>>> the presence of DT at this point since the EFI_STUB added one= already. I >>>>>>>>> guess we could move the "acpi=3Dforce" argument passing to EF= I_STUB if no >>>>>>>>> DT is present at boot. >>>>>>>> >>>>>>>> Since the EFI stub populates the /chosen node in DT, I would p= refer >>>>>>>> for it to add a property there to indicate whether it created = the DT >>>>>>>> from scratch rather than adding ACPI specific stuff in there (= even if >>>>>>>> it is just a string to concatenate) >>>>>>> >>>>>>> This works for me. So we could pass "acpi=3Dforce" in EFI stub = if it >>>>>>> created the DT from scratch *and* ACPI tables are present (can = it detect >>>>>>> the latter? And maybe it could print something if none are avai= lable). >>>>>>> If that works, the actual kernel can assume that ACPI needs to = be >>>>>>> explicitly enabled via acpi=3Dforce, irrespective of how much i= nformation >>>>>>> it has in DT. >>>>>> >>>>>> Ditto for me. I think this is a fine solution. And, yes, the stu= b can >>>>>> easily detect the presence of ACPI by looking in the UEFI config= table. >>>>> >>>>> I get the point behind doing this, but could we not have it pass = in a >>>>> different parameter than =3Dforce? Perhaps something new? I'd lik= e to >>>>> separate out the case that it was enabled automatically vs explic= itly >>>>> forced on by a user wanting to use ACPI on a system with both tab= les. >>>> >>>> Ard had a point, so we should probably not pass acpi=3Dforce from = EFI stub >>>> (especially since a user may explicitly pass acpi=3Doff irrespecti= ve of DT >>>> presence). Some other property in the chosen node? It's not even a= n ABI >>>> since that's a contract between EFI stub and the rest of the kerne= l, so >>>> an in-kernel only interface. >>> >>> Not strictly true once kexec is in place. Then it becomes a stub -> >>> kernel -> kernel -> kernel -> ... interface, alnog with the rest of= the >>> properties the stub puts in the DTB. >>> >>> Having something like /chosen/linux,uefi-stub-generated-dtb sounds = sane >>> regardless. >> >> How about the patch (just RFC, maybe it is horrible :) ) below: >> >> When system supporting both DT and ACPI but firmware providing >> no dtb, we can use this linux,uefi-stub-generated-dtb property >> to let kernel know that we can try ACPI configuration data. >> >> Signed-off-by: Hanjun Guo >> --- >> Documentation/devicetree/bindings/chosen.txt | 19 +++++++++++++++= + >> arch/arm64/kernel/setup.c | 34 >> +++++++++++++++++++++++++++- >> drivers/firmware/efi/libstub/fdt.c | 6 +++++ >> 3 files changed, 58 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/devicetree/bindings/chosen.txt >> b/Documentation/devicetree/bindings/chosen.txt >> index ed838f4..18776b9 100644 >> --- a/Documentation/devicetree/bindings/chosen.txt >> +++ b/Documentation/devicetree/bindings/chosen.txt >> @@ -44,3 +44,22 @@ Implementation note: Linux will look for the prop= erty >> "linux,stdout-path" or >> on PowerPC "stdout" if "stdout-path" is not found. However, the >> "linux,stdout-path" and "stdout" properties are deprecated. New p= latforms >> should only use the "stdout-path" property. >> + >> + >> +linux,uefi-stub-generated-dtb property >> +-------------------------------------- >> + >> +UEFI stub will generate this property in the chosen node to let lin= ux >> kernel >> +know that there is no DTB provided by firmware. >> + >> +There is a use case for system supporting both DT and ACPI, when fi= rmware >> +doesn't provide DT, we can try ACPI configration data to boot the s= ystem. > > I don't think we need to list potential use cases here, this can be > useful regardless of UEFI. OK. > > The other UEFI stub properties currently live under > Documentation/arm/uefi.txt. This should live with them. OK, will update in next version. > >> + >> +Usage: >> + >> +linux,uefi-stub-generated-dtb =3D "true" means that it is true that= the dtb >> +is generated by uefi stub >> + >> +or >> + >> +linux,uefi-stub-generated-dtb =3D "false" is the reverse. > > I imagined this would be an empty property. It would only be present = if > the stub generated the DTB, and has no value: > > /chosen { > linux,uefi-stub-generated-dtb; > }; > >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 54e39e3..8268c7b 100644 >> --- a/arch/arm64/kernel/setup.c >> +++ b/arch/arm64/kernel/setup.c >> @@ -371,6 +371,31 @@ static void __init request_standard_resources(v= oid) >> } >> } >> >> +int __init dt_scan_chosen(unsigned long node, const char *uname, >> + int depth, void *data) >> +{ >> + const char *p; >> +=09 >> + if (depth !=3D 1 || !data || >> + (strcmp(uname, "chosen") !=3D 0 && strcmp(uname, "chosen@0") != =3D 0)) >> + return 0; > > Do we ever generate chosen@0, and do we even accept that? Sorry, I have limited knowledge about the history of DT, so I think you meant that I just need to check strcmp(uname, "chosen") here, right? > >> + >> + p =3D of_get_flat_dt_prop(node, "linux,uefi-stub-generated-dtb", N= ULL); >> + if (!p && !strcmp(p, "true")) >> + *data =3D true; >> + >> + return 1; >> +} >> + >> +static bool __init is_uefi_stub_generated_dtb(void) >> +{ >> + bool flag =3D false; >> + >> + of_scan_flat_dt(dt_scan_chosen, &flag); >> + >> + return flag; >> +} >> + >> u64 __cpu_logical_map[NR_CPUS] =3D { [0 ... NR_CPUS-1] =3D INVALI= D_HWID }; >> >> void __init setup_arch(char **cmdline_p) >> @@ -389,7 +414,14 @@ void __init setup_arch(char **cmdline_p) >> early_fixmap_init(); >> early_ioremap_init(); >> >> - disable_acpi(); >> + /* >> + * If no dtb provided by firmware, enable ACPI >> + * and try to boot with ACPI configuration data >> + */ >> + if (is_uefi_stub_generated_dtb()) >> + enable_acpi(); >> + else >> + disable_acpi(); >> >> parse_early_param(); >> >> diff --git a/drivers/firmware/efi/libstub/fdt.c >> b/drivers/firmware/efi/libstub/fdt.c >> index c846a96..9e2084b 100644 >> --- a/drivers/firmware/efi/libstub/fdt.c >> +++ b/drivers/firmware/efi/libstub/fdt.c >> @@ -154,6 +154,12 @@ efi_status_t update_fdt(efi_system_table_t >> *sys_table, void *orig_fdt, >> if (status) >> goto fdt_set_fail; >> >> + /* Add a property to show the dtb is generated by uefi stub or not= */ >> + status =3D fdt_setprop_string(fdt, node, "linux,uefi-stub-generate= d-dtb", >> + orig_fdt ? "false" : "true"); >> + if (status) >> + goto fdt_set_fail; >> + > > This should create an empty property, and only when generated by the > stub. OK. could you give me some guidance to use which API to create an empty property? I try to find but failed. Thanks for the review! Hanjun -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html