[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] xen/arch/x86: Fix early boot command line parsing
On 03/12/13 20:28, Daniel Kiper wrote: > There is no reliable way to encode NUL character as a character so encode > it as a number. Read: http://sourceware.org/binutils/docs/as/Characters.html. > Octal and hex encoding do not work on at least one system (GNU assembler > version 2.22 (x86_64-linux-gnu) using BFD version (GNU Binutils for Debian) > 2.22). > Without this fix e.g. no-real-mode option at the end of xen.gz command line > is not detected. > > v2 - suggestions/fixes: > - add relevant comment to assembly file > (suggested by Andrew Cooper), > - leave encoding of other characters as is for readability > (suggested by Jan Beulich). > > Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx> I was thinking more along the lines of /* NULL check (as $'\0' == 0x30 in GAS) */ Either way, at least it is obvious. Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > --- > xen/arch/x86/boot/cmdline.S | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/x86/boot/cmdline.S b/xen/arch/x86/boot/cmdline.S > index 05ffb94..b83975e 100644 > --- a/xen/arch/x86/boot/cmdline.S > +++ b/xen/arch/x86/boot/cmdline.S > @@ -138,7 +138,15 @@ > call .Lstrlen > add $4,%esp > xadd %eax,%ebx > - cmpb $'\0',(%ebx) > + /* > + * There is no reliable way to encode NUL character as a character > so encode > + * it as a number. Read: > http://sourceware.org/binutils/docs/as/Characters.html. > + * Octal and hex encoding do not work on at least one system (GNU > assembler > + * version 2.22 (x86_64-linux-gnu) using BFD version (GNU Binutils > for Debian) 2.22). > + * Without this fix e.g. no-real-mode option at the end of xen.gz > command line > + * is not detected. > + */ > + cmpb $0,(%ebx) > je 3f > cmpb $' ',(%ebx) > je 3f _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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