On Wed, 16 Feb 2011 23:41:26 +0100, Alexander Best <arun...@freebsd.org>
wrote:
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.
You guys are kings. :-) I heard they don't even teach assembly anymore at
a lot of universities.
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
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