These are the packages that would be merged, in order:

Calculating dependencies... done!

!!! All ebuilds that could satisfy "sys-kernel/linux-firmware" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-kernel/linux-firmware-99999999::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s), missing keyword)
A copy of the 'linux-fw-redistributable' license is located at '/var/db/repos/gentoo/licenses/linux-fw-redistributable'.

A copy of the 'no-source-code' license is located at '/var/db/repos/gentoo/licenses/no-source-code'.

- sys-kernel/linux-firmware-20230117::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s), ~amd64 keyword)
- sys-kernel/linux-firmware-20221214::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20221109::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20221012-r1::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s), ~amd64 keyword)
- sys-kernel/linux-firmware-20221012::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220913-r2::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220815::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220708::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220610::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220509::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220411::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220310::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))
- sys-kernel/linux-firmware-20220209::gentoo (masked by: || ( ) linux-fw-redistributable no-source-code license(s))

(dependency required by "sys-kernel/genkernel-4.2.6-r8::gentoo[firmware]" [ebuild])
(dependency required by "sys-kernel/genkernel" [argument])
For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.

解决办法:
nano /etc/portage/package.license
添加：
sys-kernel/linux-firmware  linux-fw-redistributable no-source-code