From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752728AbbATJ3p (ORCPT ); Tue, 20 Jan 2015 04:29:45 -0500 Received: from mail-pa0-f51.google.com ([209.85.220.51]:44234 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751614AbbATJ3m (ORCPT ); Tue, 20 Jan 2015 04:29:42 -0500 Message-ID: <54BE1FEA.5040109@linaro.org> Date: Tue, 20 Jan 2015 17:29:14 +0800 From: Hanjun Guo User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Mark Rutland , Catalin Marinas CC: "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 Subject: Re: [PATCH v7 04/17] ARM64 / ACPI: Introduce early_param for "acpi" and pass acpi=force to enable ACPI 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> In-Reply-To: <20150119180122.GJ21553@leverpostej> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. + +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. 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; + + 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; + return EFI_SUCCESS; fdt_set_fail: