Date: Sat, 05 May 2012 12:31:22 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: John Baldwin <jhb@FreeBSD.org> Cc: freebsd-fs@FreeBSD.org, freebsd-hackers@FreeBSD.org Subject: Re: [review request] zfsboot/zfsloader: support accessing filesystems within a pool Message-ID: <4FA4F36A.6030903@FreeBSD.org> In-Reply-To: <201205041125.15155.jhb@freebsd.org> References: <4F8999D2.1080902@FreeBSD.org> <4FA29E1B.7040005@FreeBSD.org> <4FA2A307.2090108@FreeBSD.org> <201205041125.15155.jhb@freebsd.org>
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on 04/05/2012 18:25 John Baldwin said the following: > On Thursday, May 03, 2012 11:23:51 am Andriy Gapon wrote: >> on 03/05/2012 18:02 Andriy Gapon said the following: >>> >>> Here's the latest version of the patches: >>> http://people.freebsd.org/~avg/zfsboot.patches.4.diff >> >> I've found a couple of problems in the previous version, so here's another one: >> http://people.freebsd.org/~avg/zfsboot.patches.5.diff >> The important change is in the first patch (__exec args). > > A few comments/suggestions on the args bits: John, these are excellent suggestions! Thank you! Some comments: > - Please move the type of the 'kargs' struct into the new header and > give it a type name. Don't add the LOADER_ZFS_SUPPORT #ifdef's > however or the new size field (see below). Done. I've named the header and the struct "bootargs". > - Add #ifndef LOCORE guards to the new header around the structure so > it can be used in assembly as well as C. Done. I have had to go into a few btx makefiles and add a necessary include path and -DLOCORE to make the header usable from asm. > - Move BI_SIZE and ARGOFF into the header as constants. Done. > - Add a CTASSERT() in loader/main.c that BI_SIZE == sizeof(struct bootinfo) I have added a definition of CTASSERT to boostrap.h as it was not available for sys/boot and there were two local definitions of the macro in individual files. However the assertion would fail right now. The backward-compatible value of BI_SIZE (72 == 0x48) covers only part of the fields in struct bootinfo, those up to the following comment: /* Items below only from advanced bootloader */ I am a little bit hesitant: should I increase BI_SIZE to cover the whole struct bootinfo or should I compare BI_SIZE to offsetof bi_kernend? > - Add a KA_SIZE for sizeof(struct kargs) with a CTASSERT. Use it in this > instruction: Done. > + addl 0x1c(%esp),%ecx # Add size of variable args > > in place of the 0x1c Done. Plus some more. > - Don't add the new 'size' field to the end of the 'struct kargs'. Instead > add a comment saying that if KARGS_FLAGS_EXT is set, then a structure will > be present at (kargs + 1) that has a int size as its first member. Done. > Maybe > create a 'struct kargs_ext' that looks like this: > > struct kargs_ext { > uint32_t size; > char data[0]; > }; I've decided to skip on this. > - Use 'zargs = (struct zfs_boot_args)(kargs + 1)' in loader/main.c. > - Change the ARGADJ line in btxcsu to be this: > > .set ARGADJ,0x1000 - ARGOFF I've decided to define ARGADJ in the new common header, then I've had to rename btxcsu.s to .S, so that the preprocessing is executed for it. > - If you are adventurous, you could even add a new constant ARGSPACE or some > such with an appropriate comment in the new header that you use to replace > the 0x1000 in btx.S and in the definition of ARGADJ. Done. > Hope that isn't too much, but I do think this will help make things even more > understandable. > I will send the new patch shortly. -- Andriy Gapon
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