From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zhang, Jonathan Zhixiong" Subject: Re: [PATCH V4 1/4] efi: x86: rearrange efi_mem_attributes() Date: Mon, 15 Jun 2015 15:24:46 -0700 Message-ID: <557F50AE.50403@codeaurora.org> References: <1434157307-32318-1-git-send-email-zjzhang@codeaurora.org> <1434157307-32318-2-git-send-email-zjzhang@codeaurora.org> <20150615170957.GC17685@codeblueprint.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150615170957.GC17685-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Matt Fleming Cc: Matt Fleming , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, ying.huang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, fu.wei-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, al.stone-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-efi@vger.kernel.org On 6/15/2015 10:09 AM, Matt Fleming wrote: > On Fri, 12 Jun, at 06:01:44PM, Jonathan (Zhixiong) Zhang wrote: >> From: "Jonathan (Zhixiong) Zhang" >> >> x86 and ia64 implement efi_mem_attributes() differently. This >> function needs to be available for other arch (such as arm64) >> as well, such as for the purpose of ACPI/APEI. >> >> ia64 efi does not setup memmap variable and does not set >> EFI_MEMMAP flag, so it needs to have its unique implementation >> of efi_mem_attributes(). > > Something like the above paragraph... > >> @@ -517,3 +517,21 @@ char * __init efi_md_typeattr_format(char *buf, size_t size, >> attr & EFI_MEMORY_UC ? "UC" : ""); >> return buf; >> } > > needs to go here, i.e. as documentation for efi_mem_atributes(). You > need to explain why this function is marked as __weak at the function > definition site. > >> +u64 __weak efi_mem_attributes(unsigned long phys_addr) >> +{ >> + efi_memory_desc_t *md; >> + void *p; >> + >> + if (!efi_enabled(EFI_MEMMAP)) >> + return 0; >> + >> + for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { >> + md = p; >> + if ((md->phys_addr <= phys_addr) && >> + (phys_addr < (md->phys_addr + >> + (md->num_pages << EFI_PAGE_SHIFT)))) >> + return md->attribute; >> + } >> + return 0; >> +} > > because otherwise people are going to read this in the future and think, > > "efi_mem_attribute() doesn't quite work how I want it to for my arch, > but it's __weak, so I'll override it" > > which is absolutely not the practice we should be promoting. > > How about something like this, > > /* > * efi_mem_attributes - lookup memmap attributes for physical address > * @phys_addr: the physical address to lookup > * > * Search in the EFI memory map for the region covering > * @phys_addr. Returns the EFI memory attributes if the region > * was found in the memory map, 0 otherwise. > * > * Despite being marked __weak most architectures should *not* > * override this function. It is __weak solely for the benefit > * of ia64 which has a funky EFI memory map that doesn't work > * the same way as other architectures. > */ > Thank you Matt for the suggestion. Will do so accordingly. -- Jonathan (Zhixiong) Zhang The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project