From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland 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 11:10:32 +0000 Message-ID: <20150120111032.GB15924@leverpostej> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <54BE1FEA.5040109@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Hanjun Guo 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 List-Id: linux-acpi@vger.kernel.org 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. >=20 > How about the patch (just RFC, maybe it is horrible :) ) below: >=20 > 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. >=20 > Signed-off-by: Hanjun Guo > --- > Documentation/devicetree/bindings/chosen.txt | 19 ++++++++++++++++ > arch/arm64/kernel/setup.c | 34=20 > +++++++++++++++++++++++++++- > drivers/firmware/efi/libstub/fdt.c | 6 +++++ > 3 files changed, 58 insertions(+), 1 deletion(-) >=20 > diff --git a/Documentation/devicetree/bindings/chosen.txt=20 > 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 prope= rty=20 > "linux,stdout-path" or > on PowerPC "stdout" if "stdout-path" is not found. However, the > "linux,stdout-path" and "stdout" properties are deprecated. New pla= tforms > 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 linu= x=20 > kernel > +know that there is no DTB provided by firmware. > + > +There is a use case for system supporting both DT and ACPI, when fir= mware > +doesn't provide DT, we can try ACPI configration data to boot the sy= stem. I don't think we need to list potential use cases here, this can be useful regardless of UEFI. The other UEFI stub properties currently live under Documentation/arm/uefi.txt. This should live with them. > + > +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(vo= id) > } > } >=20 > +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? > + > + p =3D of_get_flat_dt_prop(node, "linux,uefi-stub-generated-dtb", NU= LL); > + 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 INVALID_= HWID }; >=20 > void __init setup_arch(char **cmdline_p) > @@ -389,7 +414,14 @@ void __init setup_arch(char **cmdline_p) > early_fixmap_init(); > early_ioremap_init(); >=20 > - 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(); >=20 > parse_early_param(); >=20 > diff --git a/drivers/firmware/efi/libstub/fdt.c=20 > 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=20 > *sys_table, void *orig_fdt, > if (status) > goto fdt_set_fail; >=20 > + /* Add a property to show the dtb is generated by uefi stub or not = */ > + status =3D fdt_setprop_string(fdt, node, "linux,uefi-stub-generated= -dtb", > + orig_fdt ? "false" : "true"); > + if (status) > + goto fdt_set_fail; > + This should create an empty property, and only when generated by the stub. Thanks, Mark. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754574AbbATLLB (ORCPT ); Tue, 20 Jan 2015 06:11:01 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:38931 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754418AbbATLK6 (ORCPT ); Tue, 20 Jan 2015 06:10:58 -0500 Date: Tue, 20 Jan 2015 11:10:32 +0000 From: Mark Rutland To: Hanjun Guo 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.org" , "graeme.gregory@linaro.org" , Randy Dunlap , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , "suravee.suthikulpanit@amd.com" , Sudeep Holla , Olof Johansson , leif.lindholm@linaro.org Subject: Re: [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI Message-ID: <20150120111032.GB15924@leverpostej> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <54BE1FEA.5040109@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 20, 2015 at 09:29:14AM +0000, Hanjun Guo wrote: > On 2015年01月20日 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=off > >>>>>>>> will be the default behavior for ARM64, so introduce acpi=force to > >>>>>>>> enable ACPI on ARM64. > >>>>>>>> > >>>>>>>> Disable ACPI before early parameters parsed, and enable it to pass > >>>>>>>> "acpi=force" if people want use ACPI on ARM64. This ensures DT be > >>>>>>>> the prefer one if ACPI table and DT both are provided at this 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 kernel to > >>>>>>> ignore ACPI altogether if DT is not present? It's a bit harder to detect > >>>>>>> the presence of DT at this point since the EFI_STUB added one already. I > >>>>>>> guess we could move the "acpi=force" argument passing to EFI_STUB if no > >>>>>>> DT is present at boot. > >>>>>> > >>>>>> Since the EFI stub populates the /chosen node in DT, I would prefer > >>>>>> 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=force" 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 available). > >>>>> If that works, the actual kernel can assume that ACPI needs to be > >>>>> explicitly enabled via acpi=force, irrespective of how much information > >>>>> it has in DT. > >>>> > >>>> Ditto for me. I think this is a fine solution. And, yes, the stub 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 =force? Perhaps something new? I'd like to > >>> separate out the case that it was enabled automatically vs explicitly > >>> forced on by a user wanting to use ACPI on a system with both tables. > >> > >> Ard had a point, so we should probably not pass acpi=force from EFI stub > >> (especially since a user may explicitly pass acpi=off irrespective of DT > >> presence). Some other property in the chosen node? It's not even an ABI > >> since that's a contract between EFI stub and the rest of the kernel, 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 property > "linux,stdout-path" or > on PowerPC "stdout" if "stdout-path" is not found. However, the > "linux,stdout-path" and "stdout" properties are deprecated. New platforms > 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 linux > kernel > +know that there is no DTB provided by firmware. > + > +There is a use case for system supporting both DT and ACPI, when firmware > +doesn't provide DT, we can try ACPI configration data to boot the system. I don't think we need to list potential use cases here, this can be useful regardless of UEFI. The other UEFI stub properties currently live under Documentation/arm/uefi.txt. This should live with them. > + > +Usage: > + > +linux,uefi-stub-generated-dtb = "true" means that it is true that the dtb > +is generated by uefi stub > + > +or > + > +linux,uefi-stub-generated-dtb = "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(void) > } > } > > +int __init dt_scan_chosen(unsigned long node, const char *uname, > + int depth, void *data) > +{ > + const char *p; > + > + if (depth != 1 || !data || > + (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0)) > + return 0; Do we ever generate chosen@0, and do we even accept that? > + > + p = of_get_flat_dt_prop(node, "linux,uefi-stub-generated-dtb", NULL); > + if (!p && !strcmp(p, "true")) > + *data = true; > + > + return 1; > +} > + > +static bool __init is_uefi_stub_generated_dtb(void) > +{ > + bool flag = false; > + > + of_scan_flat_dt(dt_scan_chosen, &flag); > + > + return flag; > +} > + > u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_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 = fdt_setprop_string(fdt, node, "linux,uefi-stub-generated-dtb", > + orig_fdt ? "false" : "true"); > + if (status) > + goto fdt_set_fail; > + This should create an empty property, and only when generated by the stub. Thanks, Mark. From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Tue, 20 Jan 2015 11:10:32 +0000 Subject: [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI In-Reply-To: <54BE1FEA.5040109@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> Message-ID: <20150120111032.GB15924@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Jan 20, 2015 at 09:29:14AM +0000, Hanjun Guo wrote: > On 2015?01?20? 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=off > >>>>>>>> will be the default behavior for ARM64, so introduce acpi=force to > >>>>>>>> enable ACPI on ARM64. > >>>>>>>> > >>>>>>>> Disable ACPI before early parameters parsed, and enable it to pass > >>>>>>>> "acpi=force" if people want use ACPI on ARM64. This ensures DT be > >>>>>>>> the prefer one if ACPI table and DT both are provided at this 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 kernel to > >>>>>>> ignore ACPI altogether if DT is not present? It's a bit harder to detect > >>>>>>> the presence of DT at this point since the EFI_STUB added one already. I > >>>>>>> guess we could move the "acpi=force" argument passing to EFI_STUB if no > >>>>>>> DT is present at boot. > >>>>>> > >>>>>> Since the EFI stub populates the /chosen node in DT, I would prefer > >>>>>> 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=force" 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 available). > >>>>> If that works, the actual kernel can assume that ACPI needs to be > >>>>> explicitly enabled via acpi=force, irrespective of how much information > >>>>> it has in DT. > >>>> > >>>> Ditto for me. I think this is a fine solution. And, yes, the stub 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 =force? Perhaps something new? I'd like to > >>> separate out the case that it was enabled automatically vs explicitly > >>> forced on by a user wanting to use ACPI on a system with both tables. > >> > >> Ard had a point, so we should probably not pass acpi=force from EFI stub > >> (especially since a user may explicitly pass acpi=off irrespective of DT > >> presence). Some other property in the chosen node? It's not even an ABI > >> since that's a contract between EFI stub and the rest of the kernel, 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 property > "linux,stdout-path" or > on PowerPC "stdout" if "stdout-path" is not found. However, the > "linux,stdout-path" and "stdout" properties are deprecated. New platforms > 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 linux > kernel > +know that there is no DTB provided by firmware. > + > +There is a use case for system supporting both DT and ACPI, when firmware > +doesn't provide DT, we can try ACPI configration data to boot the system. I don't think we need to list potential use cases here, this can be useful regardless of UEFI. The other UEFI stub properties currently live under Documentation/arm/uefi.txt. This should live with them. > + > +Usage: > + > +linux,uefi-stub-generated-dtb = "true" means that it is true that the dtb > +is generated by uefi stub > + > +or > + > +linux,uefi-stub-generated-dtb = "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(void) > } > } > > +int __init dt_scan_chosen(unsigned long node, const char *uname, > + int depth, void *data) > +{ > + const char *p; > + > + if (depth != 1 || !data || > + (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen at 0") != 0)) > + return 0; Do we ever generate chosen at 0, and do we even accept that? > + > + p = of_get_flat_dt_prop(node, "linux,uefi-stub-generated-dtb", NULL); > + if (!p && !strcmp(p, "true")) > + *data = true; > + > + return 1; > +} > + > +static bool __init is_uefi_stub_generated_dtb(void) > +{ > + bool flag = false; > + > + of_scan_flat_dt(dt_scan_chosen, &flag); > + > + return flag; > +} > + > u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_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 = fdt_setprop_string(fdt, node, "linux,uefi-stub-generated-dtb", > + orig_fdt ? "false" : "true"); > + if (status) > + goto fdt_set_fail; > + This should create an empty property, and only when generated by the stub. Thanks, Mark.