[SLOF] [PATCH v2 07/11] libnet: Wire up pxelinux.cfg network booting

[Thomas Huth]

On 25.05.2018 04:44, Alexey Kardashevskiy wrote:
> On 25/5/18 12:39 am, Thomas Huth wrote:
>> On 24.05.2018 11:01, Alexey Kardashevskiy wrote:
>>> On 19/5/18 1:45 am, Thomas Huth wrote:
>>>> In case the normal network loading failed, try to load a pxelinux.cfg
>>>> config file. If that succeeds, load the kernel and initrd with the
>>>> information that could be found in this file.
>>>>
>>>> Signed-off-by: Thomas Huth <thuth at redhat.com>
>>>> ---
>>>>  include/helpers.h    |  2 ++
>>>>  lib/libnet/netload.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>>  slof/helpers.c       | 15 ++++++++++---
>>>>  3 files changed, 73 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/include/helpers.h b/include/helpers.h
>>>> index 04ee771..9dfe3ae 100644
>>>> --- a/include/helpers.h
>>>> +++ b/include/helpers.h
>>>> @@ -36,6 +36,8 @@ extern void SLOF_pci_config_write16(long offset, long value);
>>>>  extern void SLOF_pci_config_write8(long offset, long value);
>>>>  extern void *SLOF_translate_my_address(void *addr);
>>>>  extern int write_mm_log(char *data, unsigned int len, unsigned short type);
>>>> +extern void SLOF_set_chosen_int(const char *s, long val);
>>>> +extern void SLOF_set_chosen_bytes(const char *s, const char *addr, size_t size);
>>>>  extern void SLOF_encode_bootp_response(void *addr, size_t size);
>>>>  extern void SLOF_encode_dhcp_response(void *addr, size_t size);
>>>>  
>>>> diff --git a/lib/libnet/netload.c b/lib/libnet/netload.c
>>>> index ba1008c..2a2a7c5 100644
>>>> --- a/lib/libnet/netload.c
>>>> +++ b/lib/libnet/netload.c
>>>> @@ -26,6 +26,7 @@
>>>>  #include <helpers.h>
>>>>  #include "args.h"
>>>>  #include "netapps.h"
>>>> +#include "pxelinux.h"
>>>>  
>>>>  #define IP_INIT_DEFAULT 5
>>>>  #define IP_INIT_NONE    0
>>>> @@ -425,6 +426,60 @@ static int tftp_load(filename_ip_t *fnip, void *buffer, int len)
>>>>  	return rc;
>>>>  }
>>>>  
>>>> +#define CFG_BUF_SIZE 2048
>>>> +#define MAX_LKIA_ENTRIES 16
>>>> +static int net_pxelinux_cfg_load(filename_ip_t *fnip, char *loadbase,
>>>> +                                 int maxloadlen, uint8_t *mac)
>>>
>>>
>>> The name confused me, there is already pxelinux_load_cfg().
>>> net_pxelinux_load() may be?
>>
>> Sure, I'll rename it.
>>
>>>> +{
>>>> +	static char cfgbuf[CFG_BUF_SIZE];
>>>
>>> This belongs to pxelinux_load_parse_cfg().
>>
>> The pointer in the struct lkia entries[] below will point to the
>> original location in the above buffer, so this cfgbuf needs to remain
>> valid until the end of this function. That means, the memory for the
>> buffer should be managed in the calling function instead of doing it in
>> pxelinux_load_parse_cfg(). I should maybe update the comments there to
>> make this clear... Alternatively, I could also "strdup" the strings for
>> the struct lkia entries, but then this caller here has to make sure to
>> free the strings again once the information from struct lkia is not
>> needed anymore - and IMHO that's uglier and more error-prone than to
>> allocate the cfgbuf buffer here on the calling site.
> 
> 
> Open coding pxelinux_load_parse_cfg() here would have eliminated the
> question in the first place. You export pxelinux_parse_cfg() anyway even
> though you do not use it outside lib/libnet/pxelinux.c.

Please keep in mind that the s390-ccw bios is using now libnet, too.
That's the reason for putting the code in pxelinux.c, while keeping the
"controlling" code in netload.c. Think of pxelinux.c being the library,
and netload.c the "program" that uses the library. I also plan to call
pxelinux_parse_cfg() from the outside in the s390-ccw bios, so that
function needs to be non-static.

 Thomas