Date: Wed, 16 Feb 2011 22:41:26 +0000 From: Alexander Best <arundel@freebsd.org> To: Warner Losh <imp@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r218745 - head/sys/boot/i386/boot2 Message-ID: <20110216224126.GA47777@freebsd.org> In-Reply-To: <20110216221712.GA44796@freebsd.org> References: <201102161805.p1GI5ABX078768@svn.freebsd.org> <20110216221014.GA43296@freebsd.org> <20110216221712.GA44796@freebsd.org>
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On Wed Feb 16 11, Alexander Best wrote: > On Wed Feb 16 11, Alexander Best wrote: > > On Wed Feb 16 11, Warner Losh wrote: > > > Author: imp > > > Date: Wed Feb 16 18:05:10 2011 > > > New Revision: 218745 > > > URL: http://svn.freebsd.org/changeset/base/218745 > > > > > > Log: > > > Remove reading of symbols from a.out loaded files. Since we are tight > > > on space for clang and a.out support is only needed for /boot/loader, > > > they are excess bytes that serve no useful purpose other than to > > > support really old kernels (FreeBSD < 3.2 or so). Prefer clang > > > support over support for these old kernels and remove this code. We > > > gain about 100 bytes of space this way. > > > > i think without this code uint32_t x serves no purpose any longer: > > > > /usr/git-freebsd-head/sys/boot/i386/boot2/boot2.c:322:20: warning: unused variable 'x' [-Wunused-variable] > > uint32_t addr, x; > > ^ > > also due to > > /usr/git-freebsd-head/sys/boot/i386/boot2/boot2.c:631:8: warning: cast from 'caddr_t' (aka 'char *') to 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Wcast-align] > t1 = *(uint32_t *)PTOV(0x46c); > ^~~~~~~~~~~~~~~~~~~~~~~ > > i think t0 and t1 can be turned into uint8_t's and PTOV(0x46c); can be casted > to (uint8_t *), instead of (uint32_t *). with this additional change the code fits when compiled with clang: diff --git a/sys/boot/i386/boot2/sio.S b/sys/boot/i386/boot2/sio.S index 7b8e9eb..d745129 100644 --- a/sys/boot/i386/boot2/sio.S +++ b/sys/boot/i386/boot2/sio.S @@ -29,11 +29,11 @@ sio_init: movw $SIO_PRT+0x3,%dx # Data format reg movb $SIO_FMT|0x80,%al # Set format outb %al,(%dx) # and DLAB - pushl %edx # Save + pushb %dl # Save subb $0x3,%dl # Divisor latch reg movl 0x8(%esp),%eax # Set outw %ax,(%dx) # BPS - popl %edx # Restore + popb %dl # Restore movb $SIO_FMT,%al # Clear outb %al,(%dx) # DLAB incl %edx # Modem control reg ...since we're only modifying %dl in subb $0x3,%dl, we don't need to push/pop a 32 bit value, but only 8 bits. cheers. alex > > cheers. > alex > > > > > cheers. > > alex > > > > > > > > Reviewed by: rdivacky@ > > > > > > Modified: > > > head/sys/boot/i386/boot2/boot2.c > > > > > > Modified: head/sys/boot/i386/boot2/boot2.c > > > ============================================================================== > > > --- head/sys/boot/i386/boot2/boot2.c Wed Feb 16 17:50:21 2011 (r218744) > > > +++ head/sys/boot/i386/boot2/boot2.c Wed Feb 16 18:05:10 2011 (r218745) > > > @@ -347,23 +347,6 @@ load(void) > > > p += roundup2(hdr.ex.a_text, PAGE_SIZE); > > > if (xfsread(ino, p, hdr.ex.a_data)) > > > return; > > > - p += hdr.ex.a_data + roundup2(hdr.ex.a_bss, PAGE_SIZE); > > > - bootinfo.bi_symtab = VTOP(p); > > > - *(uint32_t*)p = hdr.ex.a_syms; > > > - p += sizeof(hdr.ex.a_syms); > > > - if (hdr.ex.a_syms) { > > > - if (xfsread(ino, p, hdr.ex.a_syms)) > > > - return; > > > - p += hdr.ex.a_syms; > > > - if (xfsread(ino, p, sizeof(int))) > > > - return; > > > - x = *(uint32_t *)p; > > > - p += sizeof(int); > > > - x -= sizeof(int); > > > - if (xfsread(ino, p, x)) > > > - return; > > > - p += x; > > > - } > > > } else { > > > fs_off = hdr.eh.e_phoff; > > > for (j = i = 0; i < hdr.eh.e_phnum && j < 2; i++) { > > > @@ -395,8 +378,8 @@ load(void) > > > } > > > } > > > addr = hdr.eh.e_entry & 0xffffff; > > > + bootinfo.bi_esymtab = VTOP(p); > > > } > > > - bootinfo.bi_esymtab = VTOP(p); > > > bootinfo.bi_kernelname = VTOP(kname); > > > bootinfo.bi_bios_dev = dsk.drive; > > > __exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK), > > > > -- > > a13x > > -- > a13x -- a13x
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