Hi Borislav, On Sat, Sep 29, 2018 at 06:34:58PM +0200, Borislav Petkov wrote: > On Fri, Sep 28, 2018 at 05:40:08PM +0800, Feng Tang wrote: > > "pciserial" earlyprintk helps much on many modern x86 platforms, > > but unfortunately there are still some platforms whose PCI UART > > devices have wrong PCI class code, which will be blocked by current > > class code check. > > > > Add a option "force" so that developer could still use a UART device > > even it has wrong class code, with format "",B:D.F,force,baud". And > > This new parameter and its meaning needs to be documented where > pciserial is documented.
Ok, will change the kernel-parameters.txt in next version. > > > the original format ",B:D.F,baud" is kept unchanged. > > > > Suggested-by: Borislav Petkov <[email protected]> > > Signed-off-by: Feng Tang <[email protected]> > > --- > > arch/x86/kernel/early_printk.c | 26 ++++++++++++++++++++------ > > 1 file changed, 20 insertions(+), 6 deletions(-) > > > > diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c > > index 5e801c8..35d0f66 100644 > > --- a/arch/x86/kernel/early_printk.c > > +++ b/arch/x86/kernel/early_printk.c > > @@ -213,8 +213,10 @@ static unsigned int mem32_serial_in(unsigned long > > addr, int offset) > > * early_pci_serial_init() > > * > > * This function is invoked when the early_printk param starts with > > "pciserial" > > - * The rest of the param should be ",B:D.F,baud" where B, D & F describe > > the > > - * location of a PCI device that must be a UART device. > > + * The rest of the param should be ",B:D.F,baud" or ",B:D.F,force,baud", > > where > > + * B, D & F describe the location of a PCI device that must be a UART > > device, > > + * "force" is optional and means insisting using a UART device with a wrong > > + * pci class code. > > */ > > static __init void early_pci_serial_init(char *s) > > { > > @@ -224,6 +226,7 @@ static __init void early_pci_serial_init(char *s) > > u32 classcode, bar0; > > u16 cmdreg; > > char *e; > > + int force = 0; > > > > > > /* > > @@ -252,6 +255,15 @@ static __init void early_pci_serial_init(char *s) > > if (*s == ',') > > s++; > > > > + /* User may insist to use a UART device with wrong class code */ > > + if (!strncmp(s, "force", 5)) { > > + force = 1; > > + s += 5; > > + > > + if (*s == ',') > > + s++; > > No, you need to force the presence of "," otherwise cmdlines like this: > > earlyprintk=pciserial,0:XX.X,forcedoodoo > > work too. Got your point. As the following [,baudrate] is also optional, and this "force" could be the last option for pciserial. The check may be if (!strncmp(s, "force,", 6) || !strncmp(s, "force ", 6)) { force = 1; s += 6; } > > + } > > + > > /* > > * Second, find the device from the BDF > > */ > > @@ -262,10 +274,12 @@ static __init void early_pci_serial_init(char *s) > > /* > > * Verify it is a UART type device > > */ > > - if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && > > - (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || > > - (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ > > - return; > > + if (!force) { > > + if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && > > + (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || > > + (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ > > + return; > > Move the force check in here ^ Do you mean this? if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ { if (!force) return; } Thanks, Feng
