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Date: Wed, 21 Nov 2012 09:17:21 -0800 From: "H. Peter Anvin" <hpa@...or.com> To: Yinghai Lu <yinghai@...nel.org> CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>, "Eric W. Biederman" <ebiederm@...ssion.com>, linux-kernel@...r.kernel.org, Rob Landley <rob@...dley.net>, Matt Fleming <matt.fleming@...el.com> Subject: Re: [PATCH v3 11/12] x86, boot: add fields to support load bzImage and ramdisk high On 11/20/2012 11:16 PM, Yinghai Lu wrote: > > diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt > index 9efceff..a8263f7 100644 > --- a/Documentation/x86/boot.txt > +++ b/Documentation/x86/boot.txt > @@ -57,6 +57,9 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment > Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI handover > protocol entry point. > > +Protocol 2.12: (Kernel 3.9) Added three fields for loading bzImage and > + ramdisk above 4G with 64bit. > + > **** MEMORY LAYOUT > > The traditional memory map for the kernel loader, used for Image or > @@ -182,7 +185,7 @@ Offset Proto Name Meaning > 0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel > 0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not > 0235/1 2.10+ min_alignment Minimum alignment, as a power of two > -0236/2 N/A pad3 Unused > +0236/2 2.12+ xloadflags Boot protocal option flags ^^^^^^^^ > 0238/4 2.06+ cmdline_size Maximum size of the kernel command line > 023C/4 2.07+ hardware_subarch Hardware subarchitecture > 0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data > @@ -193,6 +196,9 @@ Offset Proto Name Meaning > 0258/8 2.10+ pref_address Preferred loading address > 0260/4 2.10+ init_size Linear memory required during initialization > 0264/4 2.11+ handover_offset Offset of handover entry point > +0268/4 2.12+ ext_ramdisk_image ramdisk_image 32 bits "high 32 bits" presumably... > +026C/4 2.12+ ext_ramdisk_size ramdisk_size high 32 bits > +0270/4 2.12+ ext_cmd_line_ptr cmd_line_ptr high 32 bits I'm looking at these three fields and I'm getting worried about space -- there are only two more word-sized fields possible in this structure. Since these fields are not initialized (default to zero) and almost certainly aren't useful for people entering via the 16-bit entry point I think we should move them out of struct setup_header and into the remainder of struct boot_param. > diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c > index b4c913c..00678d3 100644 > --- a/arch/x86/boot/compressed/cmdline.c > +++ b/arch/x86/boot/compressed/cmdline.c > @@ -17,6 +17,9 @@ static unsigned long get_cmd_line_ptr(void) > { > unsigned long cmd_line_ptr = real_mode->hdr.cmd_line_ptr; > > + if (real_mode->hdr.version >= 0x020c) > + cmd_line_ptr |= (u64)real_mode->hdr.ext_cmd_line_ptr << 32; > + > return cmd_line_ptr; > } No. hdr.version is information from the kernel to the bootloader; it is meaningless to look at it inside the kernel. Same in a bunch of other places. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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